Why Did Stalin Turn in January and Mao Send Troops in October? — 1950, Two Decisions Reread After the Files Opened

When Japanese colonial rule ended in 1945, the Korean Peninsula was occupied and divided along the 38th parallel, with Soviet forces in the north and US forces in the south. In 1948, the Republic of Korea was established in the south, and North Korea (the Democratic People's Republic of Korea) led by Kim Il-sung established a separate government in the north. North Korea received support from Soviet supreme leader Joseph Stalin, while South Korea received support from the United States. The following year, in 1949, the Communist Party led by Mao Zedong won the civil war in China and established the People's Republic of China, while the defeated Nationalist government retreated to Taiwan. The Korean War began on June 25, 1950, when North Korean forces crossed the 38th parallel to attack the south, and Chinese forces also entered the war that autumn. Because of this, the war is entangled with decisions made not only in Seoul and Pyongyang, but also in Moscow, Beijing, and Washington.

There are two conventional views about this war. The Korean War was a Soviet war planned by Stalin and executed by Kim Il-sung. China entered the war reluctantly only after US forces crossed the 38th parallel. There is also one opposing conventional view. It is that it was a civil war that grew from within the Korean Peninsula. The first two place the decision-making in Moscow and the 38th parallel, while the third looks at forces within the Korean Peninsula rather than decisions. This article traces the two decisions pointed to by the first two views through documents, and examines the third view through three lenses that read Moscow.

Russian archives were opened in the 1990s. A 2018 paper records two things that became clear from former communist bloc countries afterwards (DOI: 10.33526/ejks.20181801.97). One is that Kim Il-sung, Stalin, and Mao Zedong were the three "main organizers" of the war. The other is that US-Soviet confrontation and the division at the 38th parallel created the origin. Chinese records were gradually opened thereafter. This article follows two decisions made in 1950. One is Stalin's consent in Moscow in late January, and the other is Mao's decision to dispatch troops in Beijing in October. This article is written primarily using Korean-language papers written after reading Russian and Chinese documents. This article does not adjudicate responsibility for the war. It only records who requested and approved what, and when, precisely as much as the documents state.

January in Moscow — A Guest of Two Months and Repeated Requests

In January 1950, Mao Zedong was in Moscow. It was his first visit after founding a new nation. On his desk was the issue of the return of the ports of Dalian and Port Arthur, which the Soviet Union held in China's Northeast (Manchuria), and the Changchun Railway. Stalin eventually accepted Mao's demands (DOI: 10.1017/jch.2026.10121). The alliance treaty between the two countries was concluded in February (DOI: 10.29323/mchina.2020.9.87.1). A 2014 South Korean paper views that through this treaty, the Soviet Union lost its only port and ice-free port opening to the Pacific. It was a significant strategic loss (DOI: 10.17331/kwp.2014.30.2.001). A 2026 study reads the same accommodation as a choice to keep China tied to the Soviet camp and protect ports and bases in the Yellow Sea (DOI: 10.1017/jch.2026.10121).

In Washington that same month, three things happened. On January 5, U.S. President Harry Truman stated that he would not intervene in Taiwan. On January 10 and 11, there were lengthy debates in the Senate and House Foreign Relations Committees. Following that came a press club speech by Secretary of State Dean Acheson outlining U.S. Asia policy. A 2002 paper in Journal of Korean History reads that the core of that speech was the China issue. The Asian defense perimeter was secondary. Korea was mentioned doubly. It was excluded from the strategic defense line in the Pacific, but among the excluded regions, it was classified as the highest priority (KCI ART000867927). According to a 2026 study, the United States made public its non-intervention policy toward Taiwan, taking advantage of Mao's visit to Moscow. The study views that this was intended to prevent the Sino-Soviet alliance from solidifying (DOI: 10.1017/jch.2026.10121).

And there was a request from Pyongyang. North Korean leader Kim Il-sung was repeatedly asking for permission to attack the South (KCI ART002403975). Until the end of 1949, Stalin strongly prevented North Korea from unifying by force (DOI: 10.17331/kwp.2014.30.2.001). At first, he insisted on peaceful unification (DOI: 10.1162/15203970051032309). In late January 1950, Stalin abruptly changed his attitude and agreed to Kim Il-sung's repeated requests (KCI ART002403975; DOI: 10.17331/kwp.2014.30.2.001). This was when Mao was still in Moscow. The fact that the Januarys of the three cities overlapped within a single month is what the documents show. The arrows connecting the three differ from scholar to scholar starting from the next section.

Stalin's Desk — From the Rejection of 1949 to the Agreement of Late January

There were two paths before Stalin. One is the path of 1949. It is to block forced unification and insist on peaceful unification (DOI: 10.1162/15203970051032309; DOI: 10.17331/kwp.2014.30.2.001). The other is permission. Documents say that in early 1950 he moved to the second path (DOI: 10.1162/15203970051032309).

The form of the permission is the core of this section. The form shown by the documents is Kim Il-sung's repeated requests and Stalin's consent to them (KCI ART002403975). A 2014 paper describes the same consent as "active support" (DOI: 10.17331/kwp.2014.30.2.001). Alongside the consent was China's promise. A 2013 paper in The Journal of Korean and Asian Studies reads it within Stalin's strategic design. The design was to get a promise to dispatch Chinese ground troops, and that design succeeded. However, Mao's promise of support was ideological, conditional, and limited, and direct troop dispatch was almost out of the question (KCI ART001775451). A 2015 paper in The Journal of Korean History notes how far Mao's consent went. Mao agreed to the initiation of the war. However, he stated that "if US forces intervene but do not cross the 38th Parallel, China will not dispatch troops" (DOI: 10.16912/tkhr.2015.03.225.231). A 2020 paper interprets that once North Korea and the Soviet Union agreed, the Chinese Communist Party could not object (DOI: 10.29323/mchina.2020.9.87.1). When and where Mao agreed, and the visits and telegrams exchanged between late January and June, are outside the scope of the abstracts read by this article. Consent and troop dispatch were different decisions, and above the promise, there was the 38th Parallel between the two.

At the same time, Stalin stopped the other. According to a 2026 study, he stopped indirectly supporting China's preparations for an attack on Taiwan. Instead, he gave Kim Il-sung the green light for an attack on the south (DOI: 10.1017/jch.2026.10121). Where is the "moment of decision" that conventional wisdom speaks of? The papers read by this article simply write "late January" (KCI ART002403975; DOI: 10.17331/kwp.2014.30.2.001). Telegrams with dates written on them are not in the scope of the abstracts read by this article. A telegram is an official communication sent by telegraph between leaders and diplomats. In this part, the words exchanged between Moscow and Beijing remained in the form of telegrams.

Whether Stalin expected or wanted US intervention is a divided question. According to a 2000 paper by Chinese historian Shen Zhihua, the documents show that Stalin carefully weighed the US reaction. And it is that he wrongly concluded that North Korean forces would quickly take over the south, leaving no time for the US to respond (DOI: 10.1162/15203970051032309). A 2014 paper stands on the same side. It views that whether the US intervened was merely a condition for deciding on war, not that drawing in intervention was the purpose itself. The US focus shifting to East Asia was a result of the war, not a motive (DOI: 10.17331/kwp.2014.30.2.001). The papers that view he wanted it see it from the three eyes reading Moscow. Documents connecting the Acheson speech and Stalin's transition are outside the scope read by this article.

Pyongyang's side of the plan also remained in documents. A 2013 paper in Military Research reads that plan. The North Pyongan faction that led the war, namely the communists on the North Korean side, had a policy of ending it quickly through regular operations. The "theory of a 200,000-strong people's uprising" raised by the South Korean Labor Party faction, who had been active in the south and moved to the north, was not considered when drawing up the plan with the Soviet military advisory group. No uprising broke out immediately after the attack either. There is an existing claim that Kim Il-sung pinned hopes on an uprising. That paper views this as having uncritically accepted remarks put forward later as an excuse for purges (DOI: 10.17934/jmhs..136.201312.95).

Thirteen Days in Beijing: Two Contradictory Telegrams and Decisions Written Over and Again

Two days after the war began on June 25, 1950, on June 27, the Soviet representative was absent from the United Nations Security Council (DOI: 10.29323/mchina.2023.12.100.167). The Security Council is the body that determines the UN's response to international disputes, and the Soviet Union was a permanent member that could block those decisions with a veto. The United States entered the war, and the dispatch of the U.S. Navy's 7th Fleet to the Taiwan Strait was announced. A 2016 paper notes that the outbreak of the war and the announcement of the 7th Fleet's dispatch shook the political and economic foundations of the new People's Republic of China (DOI: 10.18206/kapdh.37.2.201602.5).

Here, common knowledge and documents diverge for the first time. In July and August, before U.S. troops crossed the 38th Parallel, Mao Zedong and Kim Il Sung were already actively hoping for the deployment of Chinese troops. Recently released Chinese and Russian records show this (DOI: 10.17331/kwp.2014.30.2.002). Putting aside his promise to Stalin that 「troops would be dispatched if U.S. forces crossed the 38th Parallel」, Mao wanted an early deployment. A 2014 paper lists three reasons for this: preserving the achievements of the revolution, resolving the Taiwan issue, and securing influence over North Korea. That paper notes that Mao saw early deployment as a means to produce maximum effect with minimum cost (DOI: 10.17331/kwp.2014.30.2.002). It was Stalin who blocked that intent (DOI: 10.18206/kapdh.37.2.201602.5; DOI: 10.16912/tkhr.2015.03.225.231). According to the 2014 paper, considering the negative impacts of an early deployment, Stalin did not agree to the request of the two men. That paper suggests he was greatly satisfied with the new international situation created by the war. His goal also shifted from a quick battle and quick decision to a prolonged war (DOI: 10.17331/kwp.2014.30.2.002). The North Korean leadership considered winning on their own difficult from right after the U.S. Air Force began bombing. Therefore, they asked Stalin for the participation of the Soviet Air Force and Chinese troops (DOI: 10.17331/kwp.2014.30.2.002).

After the U.S.-led UN forces landed at Incheon and turned the tide of the war, China's resolve wavered, and it even notified Stalin and Kim Il Sung of its intent to suspend the troop deployment (DOI: 10.18206/kapdh.37.2.201602.5; DOI: 10.16912/tkhr.2015.03.225.231). The date of that notification is not in the papers read for this article. One paper places it after the breakthrough of the 38th Parallel (DOI: 10.17331/kwp.2014.30.2.002). On October 1, a telegram from Stalin asking for support for North Korea reached Mao. A 2013 paper in Journal of Northeast Asian Studies traces five major meetings held from that day until October 13 (DOI: 10.18013/jnar.2013.28.2.004). Two telegrams sent to Stalin after the October 2 meeting remain, and their contents contradict each other. How to read the two telegrams is a point of contention among researchers (DOI: 10.18013/jnar.2013.28.2.004). On October 5, citing security threats and Stalin's pressure, China decided to send troops (DOI: 10.18206/kapdh.37.2.201602.5). Chinese Premier Zhou Enlai met Stalin at the Black Sea (DOI: 10.18013/jnar.2013.28.2.004). Stalin showed reluctance regarding immediate air cover and the provision of weapons. On October 12, China again decided against entering the war and notified them accordingly (DOI: 10.18206/kapdh.37.2.201602.5).

The next day, October 13, is the day of decision. Chinese General Peng Dehuai argued that U.S. forces would stop their advance on a line connecting Pyongyang and Wonsan on the East Coast. Mao decided on the deployment once again. A 2016 paper describes what was decisive for that decision as follows: 「securing the northern region of North Korea without fighting」 and 「expanding the national defense line from the Yalu River to the region north of Pyongyang」 (DOI: 10.18206/kapdh.37.2.201602.5). The conclusion of the 2013 paper concerns a person. From October 1 to 13, virtually from beginning to end, the only person who insisted on entering the war and pushed it forward was Mao alone (DOI: 10.18013/jnar.2013.28.2.004). The same paper adds that a Mao-centered power structure spanning the party, government, and military made this possible. The Chinese People's Volunteer Army is the name given to the troops China sent to the Korean Peninsula in October 1950. The first campaign began on October 25. The Soviet Air Force entered on November 1, and expanded its operations into North Korean airspace on November 6 (DOI: 10.29323/mchina.2023.3.97.121). The telegram of October 1 came in the form of a request for support, and the decisions of the thirteen days that followed were written in meetings in Beijing (DOI: 10.18013/jnar.2013.28.2.004). Decisions were written three times within the thirteen days: dispatch on the 5th, no-go on the 12th, and troop deployment on the 13th (DOI: 10.18206/kapdh.37.2.201602.5).

Documents Opened Later — Russia in the 1990s, Chinese Dangan, and a Cable

This is the sequence of events, and now the order in which documents were opened. After the collapse of the Soviet Union, Soviet-era diplomatic documents were made public (DOI: 10.4324/9780203112205). A 2018 paper notes that when Russian classified documents were opened in the 1990s, new momentum was given to Korean War research (DOI: 10.33526/ejks.20181801.97). Those documents form the skeleton of sections 1 and 2. The refusal in 1949, the agreement in late January 1950, and the misjudgment of the U.S. response came from there (DOI: 10.1162/15203970051032309).

Chinese-side records were also opened. Dangan refers to official document records kept by the party and government in China. Since the 1980s, Chinese scholars first challenged the long-held explanations of the West (DOI: 10.16912/tkhr.2015.03.225.231). Historian Shen Zhihua's book was written by combining Soviet diplomatic documents with Chinese memoirs, official document collections, and research books. According to the book's introduction, it broke a mainland Chinese taboo by writing about the Korean War as something other than a heroic tale (DOI: 10.4324/9780203112205). Dangan chipped away at both sides. To the Western academic "because of breaking through the 38th Parallel," it showed the hope for early troop dispatch in July and August (DOI: 10.17331/kwp.2014.30.2.002), and to Chinese scholars' "active from the beginning," it showed the passive attitude that continued from before the outbreak of the war until after the announcement of the 7th Fleet: "if we do not cross the 38th Parallel, we will not dispatch troops" (DOI: 10.16912/tkhr.2015.03.225.231). July and August in section 3 is a passage that could not be written before these dangan were opened.

A single cable also entered the debate. It is a cable sent by Stalin to Czechoslovak Communist Party leader Gottwald on August 27, 1950. It explains the absence from the UN Security Council on June 27. A 2023 paper notes that there are many controversies and negative evaluations regarding the contents of that cable. Still, it is seen as offering a glimpse into the perception of the situation at the time (DOI: 10.29323/mchina.2023.12.100.167). How to read that cable remains divided.

U.S.-side documents were also opened. A 2018 paper looks at U.S. Central Intelligence Agency (CIA) documents. Documents declassified in the early 2000s and released in December 2016 contained inaccurate information regarding Mongolia (DOI: 10.33526/ejks.20181801.97). An opened document is not necessarily an entirely correct document. There are also major books written before documents were opened. American historian Bruce Cumings's The Origins of the Korean War. A 2025 reevaluation in Critical Review of History will be seen in the next section. Historiography is the history of how historians' interpretations of a single event have changed. The remaining two sections of this installment are historiography.

Three Eyes for Reading Moscow — Strategic Interests, Clashes with the U.S., and Origins Within the Korean Peninsula

The first eye looks at relations with China. According to a 2000 paper by historian Shen Zhihua, Stalin’s attitude was largely shaped by Sino-Soviet relations in 1949–50. These involved the intention to preserve Soviet privileges within Chinese territory and the concern that Beijing might challenge Moscow's leadership. Shen Zhihua interprets that Stalin judged North Korea's attack would increase his leverage over China (DOI: 10.1162/15203970051032309). A 2014 paper looks at ports. It argues that a war could guarantee the ice-free ports and strategic footholds in Asia lost through the February treaty. It suggests this was true regardless of victory or defeat (DOI: 10.17331/kwp.2014.30.2.001). A 2026 study notes that the suspension of support for Taiwan and Kim Il Sung's authorization happened side by side at the same point in time (DOI: 10.1017/jch.2026.10121). The weakness of this eye came from the same side. A 2023 paper agrees with Shen Zhihua's explanation regarding ice-free ports, yet asks a question. It points out that there was no comparative analysis of which mattered more: the West close to Moscow or the distant Far East (DOI: 10.29323/mchina.2023.12.100.167).

The second eye looks at the United States. A 2011 paper views the outcome of Sino-Soviet negotiations as having rendered Stalin's global security strategy useless. The war resolved that dilemma. A military clash between the U.S. and China ties down the U.S. feet in Asia. The Soviet Union gains time to solidify Europe, and its control over China grows. That is the picture drawn by that paper. It records that whoever the winner was, it was a card with nothing to lose for Stalin (KCI ART002403975). A 2019 paper looks at after the war began. According to that paper, North Korean forces did not follow Soviet operational concepts and thus missed a quick victory, while the Kremlin and Soviet military advisers remained silent initially. The interpretation is that Stalin wanted to drag out the war to tie down the enemy rather than achieve a quick victory (DOI: 10.14731/kjis.2019.4.17.1.79). A 2021 paper in 『Journal of Sino-Soviet Affairs』 gives a name to this picture. It argues that Mao was used as a tripwire to drag in Chinese forces if the U.S. military intervened (DOI: 10.21196/aprc.44.4.202102.003). A tripwire refers to a device designed like a cord that explodes when touched, causing the other side to be dragged in automatically when one side moves. The weakness of this eye was seen in Section 2. The questions are two. To whether American intervention was wanted at the end of January, a 2011 paper answers yes (KCI ART002403975), while Shen Zhihua and a 2014 paper answer no (DOI: 10.1162/15203970051032309; DOI: 10.17331/kwp.2014.30.2.001). To whether intervention was anticipated and prepared for, a 2021 paper answers with the tripwire (DOI: 10.21196/aprc.44.4.202102.003), whereas Shen Zhihua views it as a misjudgment. What the 2019 paper looked at is the choice after the war started, and another 2014 paper also records that transition as something that happened after the war began (DOI: 10.17331/kwp.2014.30.2.002). The picture of wanting it and the picture of misjudging it diverge over the exact same end of January.

The third eye looks inside the Korean peninsula. Historian Cumings's 『The Origins of the Korean War』 emphasized the internal political and social trends within Korea that pursued decolonization right after liberation. According to a 2025 reassessment, he finds the origins of the war in the clash between two forces. These are the revolutionary nationalism of Koreans and the anti-revolutionary policy of the U.S. The evaluation is that he trailblazingly analyzed the relationship between decolonization and the Cold War. Weaknesses are also recorded in the same writing. It does not particularly emphasize the diversity within Koreans. There are places where Korean leadership and political parties are inaccurately described. It is criticized for excessively emphasizing North Korea's particularity and simplifying it into a victim (DOI: 10.38080/crh.2025.05.151.314). The North Pyongan/Soviet-faction documents from Section 2 enter this eye. The policy of the side that planned the war was regular warfare and a blitzkrieg, and the uprising theory of the South Pyongan faction was not considered in the plan (DOI: 10.17934/jmhs..136.201312.95). To the eye looking at the origins within the Korean peninsula, this document gives two things together. These are that the side that conceived and led the war was the North Pyongan faction (they planned it together with the Soviet military advisory group) and that there was no uprising. Historian William Stueck's book introduction stands between the three eyes. It states that it weighs the balance between international factors and internal factors that led to the war (DOI: 10.1515/9781400847617). The first two eyes look at the same "end of January" while pulling arrows from different places, and the third eye looks at the five years preceding those arrows.

Three Eyes on Beijing — Security, Revolution, Moscow

The first eye looks at security. This is an explanation long accepted by Western academia. It states that China entered the war because the U.S. military crossed the 38th Parallel and threatened China's safety (DOI: 10.16912/tkhr.2015.03.225.231). A 2016 paper redraws this eye. Sending troops was a way to gain maximum security and economic benefits at the minimum cost. The decisive factor was the calculation to push the defense line north of Pyongyang. It notes that preventing the North Korean forces from retreating to the Northeast and protecting the core industries of the Northeast was a secondary effect. Its conclusion is that there was no objective of "expanding revolution" in the decision-making process (DOI: 10.18206/kapdh.37.2.201602.5). Another paper from 2014 compares four variables. Ideological solidarity and external security threats were background factors. It views the final variable as the internal security threat of "instability in the Northeast region." This was amid tensions with the Soviet Union (DOI: 10.17331/kwp.2014.30.2.003). A paper in the 2007 Manchuria Studies reads the Northeast as the headquarters of revolutionary war and nation-building. It notes that an excessive "passivity" theory and Cold War-centrism easily miss national strategic interests (KCI ART002740479). A 2021 paper calls Mao's eye "lips and teeth" (DOI: 10.21196/aprc.44.4.202102.003). "Lips and teeth" means that if the lips are gone the teeth feel cold, implying that if a neighbor falls, one is also in danger. The weakness of the old explanation in Western academia lies in Section 3. Mao already wanted to dispatch troops in July and August, before the 38th Parallel was breached (DOI: 10.17331/kwp.2014.30.2.002). The defense line explanation of the 2016 paper was written embracing those months of July and August (DOI: 10.18206/kapdh.37.2.201602.5). A 2015 paper views differently what Mao weighed first and foremost from the beginning. It argues that it was not whether to cross the 38th Parallel, but rather the pros and cons for consolidating the regime and the possibility of victory (DOI: 10.16912/tkhr.2015.03.225.231).

The second eye looks at revolution. Since the 1980s, Chinese scholars have argued that Mao was never passive. They contend that he viewed war with the U.S. as inevitable and was proactive in dispatching troops (DOI: 10.16912/tkhr.2015.03.225.231). The reading of a 2014 paper that "preserving revolutionary achievements" was included in the hope for early troop dispatch in July and August attaches to this eye (DOI: 10.17331/kwp.2014.30.2.002). A 2020 paper divides it into two stages. The logic of the socialist camp was strong in the stage of agreeing to start the war. The security logic of the new regime was strong in the stage of deciding to enter the war (DOI: 10.29323/mchina.2020.9.87.1). A 2008 paper looks at cultural-psychological factors. It analyzes that the new state's socialist identity and anti-imperialist role had a non-negligible impact on the decision and process of entering the war (DOI: 10.18212/cccs.2008..12.016). The weaknesses of this eye are two: the passive attitude before and after the outbreak of war shown by the archives (DOI: 10.16912/tkhr.2015.03.225.231), and the 2016 conclusion that there was no objective of "expanding revolution" in the decision-making process (DOI: 10.18206/kapdh.37.2.201602.5).

The third eye looks at Moscow. A 2023 paper views that China's main goal in 1950–51 was Taiwan. After the Soviet Union and North Korea agreed on the war, Mao had no choice but to support it, and after the U.S. entered the war, he advocated for dispatching troops. The motivation changed during the process. It views that the fundamental purpose was Stalin's trust. Upon that trust, the deterrence of the alliance and Soviet aid would stabilize the new regime and protect national security. The variable that had the greatest influence on the decision was Sino-Soviet relations (DOI: 10.1080/1547402x.2023.2268845). A paper in the 2016 Military History Research is left outside these three eyes because its reading spans all three leaders. That paper views that the three leaders placed more weight on the solidity of domestic power and national interests than on ideology (DOI: 10.17934/jmhs..141.201606.267). To this eye, the two papers in Section 3 give different things. A 2013 paper notes that Mao was alone in pushing forward (DOI: 10.18013/jnar.2013.28.2.004), and a 2016 paper notes that the non-entry on October 12 came after Stalin's reluctance (DOI: 10.18206/kapdh.37.2.201602.5). The former stands on the side that the decision was made within Beijing, while the latter stands on the side that it was tied to Soviet support. A paper that separately notes the weaknesses of this eye is not within the scope read by this article.

The fourth spot is small. A 2021 doctoral dissertation reviews five interpretations. It views that a researcher's "Greek tragedy" analogy is closest. That dissertation views that U.S. President Truman's blockade of the Taiwan Strait and the UN forces' breach of the 38th Parallel triggered Mao's intervention. Based on Mao's strategy toward the U.S. established in 1944–45, intervention was unavoidable (DOI: 10.7275/5drv-5m59). I attach the qualification of a dissertation. Historian Chen Jian re-asks in 2018, with new Chinese and Russian materials, the questions he posed some 20 years ago. What place did China hold in the formation of the war, and why and how did Mao and the leadership decide to enter the war (DOI: 10.1080/1547402x.2018.1437505)? The three eyes each hold different dates. Security holds October 13, revolution holds July and August, and Moscow holds October 1.

Where We Agree and Where We Still Differ — The Place of "If They Had Not Crossed"

There are four points where the documents this article read overlap. First, Kim Il-sung repeatedly requested it and Stalin blocked it in 1949 before agreeing in late January 1950 (KCI ART002403975; DOI: 10.17331/kwp.2014.30.2.001; DOI: 10.1162/15203970051032309). Second, Mao and Kim Il-sung wanted early Chinese troop deployment in July and August, and Stalin blocked it (DOI: 10.17331/kwp.2014.30.2.002; DOI: 10.16912/tkhr.2015.03.225.231; DOI: 10.18206/kapdh.37.2.201602.5). Third, China's decisions were repeatedly recorded on October 5, 12, and 13 (DOI: 10.18013/jnar.2013.28.2.004; DOI: 10.18206/kapdh.37.2.201602.5). Fourth, sections 1 and 2 came from Russian documents opened after the 1990s, while section 3's July and August came from later party archives (DOI: 10.33526/ejks.20181801.97; DOI: 10.4324/9780203112205).

There are also four points where they differ. First is Stalin's intent. One picture holds that he aimed to tie down the United States in late January (KCI ART002403975). A picture that intervention was merely a condition (DOI: 10.17331/kwp.2014.30.2.001) and a picture that it was a miscalculation (DOI: 10.1162/15203970051032309) stand on top of that same late January. Second is the two telegrams of October 2. How to read the two contradicting telegrams remains a point of contention among researchers (DOI: 10.18013/jnar.2013.28.2.004). Third is Mao's motivation. The three eyes of security, revolution, and Moscow diverge sharply from the preceding section. Fourth is Kim Il-sung's autonomy. The requests repeatedly came from him (KCI ART002403975), the plan was drawn up by the North Korean Workers' Party faction together with the Soviet military advisory group (DOI: 10.17934/jmhs..136.201312.95), and permission and troop deployment were out of his hands (DOI: 10.17331/kwp.2014.30.2.002).

Counterfactuals are gathered in one place. Counterfactuals are reasoning that looks at outcomes by setting up the condition "if they had not done so." There is one question: "If the US military had not crossed the 38th parallel, would China not have entered the war?" The mainstream of existing research answered yes. A 2014 paper casts doubt on that answer using the July and August archives (DOI: 10.17331/kwp.2014.30.2.002). A paper building counterfactuals around air cover is outside the scope of what this article read. This article does not answer this question.

Words of responsibility also diverge. A 2018 paper calls the three leaders the "main organizers" of the war (DOI: 10.33526/ejks.20181801.97). A 2019 paper views that Stalin placed Soviet national interests as top priority. This means the costs for allied China and North Korea were not considered (DOI: 10.14731/kjis.2019.4.17.1.79). A 2021 paper records that Mao entered the war even while anticipating profound human and material losses (DOI: 10.21196/aprc.44.4.202102.003). This article merely recounts those words and does not divide responsibility.

The two decisions remain this way. Stalin's decision was agreement to repeated requests. The papers read by this article all read that agreement within Soviet strategic goals, and differ on which goal it was — leverage against China (DOI: 10.1162/15203970051032309), a stronghold in the Far East (DOI: 10.17331/kwp.2014.30.2.001), tying down the US in Asia (KCI ART002403975), or China's promise of ground troops (KCI ART001775451). Mao's decision was an answer repeatedly written over thirteen days. How to read the weight of Moscow in that answer is where the three eyes reading Beijing diverge. The single line this article will take away is one. Both decisions are recorded in the documents not once, but multiple times.

Source Papers

• "Stalin's Korean U-Turn: The USSR's Evolving Security Strategy and the Origins of the Korean War" (2011) — KCI ART002403975 — Stalin's sudden change in late January 1950, Kim Il-sung's repeated requests, and Sino-Soviet negotiations altered global security strategy, creating a "card to play with nothing to lose."
• "The Sino-Soviet Alliance, the Korean War, and the Predicament of the CCP's Attack Plans for Taiwan, 1949–50" (2026) — DOI: 10.1017/jch.2026.10121 — Acceptance of the return of the Dalian, Lüshun, and Changchun railways, halting indirect support for Taiwan while giving Kim Il-sung a green light, and the timing of the U.S. announcement of non-intervention in Taiwan.
• "Why Did Stalin Not Support a Quick Victory for the Korean People's Army?" (2019) — DOI: 10.14731/kjis.2019.4.17.1.79 — Maximum gain/minimum risk strategy, the North Korean army not following Soviet operational concepts, the Kremlin's initial silence, and failure to consider allied costs (choices made after the outbreak of war).
• "극동에서 소련의 전략적 이익보장: 한국전쟁의 기원과 스탈린의 정책결정 동기" (2014) — DOI: 10.17331/kwp.2014.30.2.001 — Deterrence until late 1949, the shift in late January 1950, inducing intervention was not the goal, and the loss of ice-free ports due to the treaty.
• "한국전쟁 초기 중국군 조기파병을 둘러싼 스탈린, 마오쩌둥, 김일성의 동상이몽" (2014) — DOI: 10.17331/kwp.2014.30.2.002 — Hope for early deployment in July-August, Stalin's refusal, quick victory turning into a protracted war, and North Korea's requests for the Soviet air force and Chinese troops.
• "중국의 한국전쟁 참전결정과정" (2013) — DOI: 10.18013/jnar.2013.28.2.004 — Five major meetings between October 1 and 13, two contradictory telegrams on October 2, the Black Sea talks, and "Mao alone" alongside a Mao-centric power structure.
• "Mao, Stalin and the Korean War" (2012) — DOI: 10.4324/9780203112205 — Introduction to the English translation of Shen Zhihua's book, utilizing diplomatic documents released after the collapse of the Soviet Union plus Chinese memoirs and document collections, with the mainland remaining a taboo subject.
• "Sino-Soviet Relations and the Origins of the Korean War: Stalin's Strategic Goals in the Far East" (2000) — DOI: 10.1162/15203970051032309 — Shen Zhihua on insisting on peaceful unification leading to authorization in early 1950, misjudgment of the U.S. response, concerns over privileges and leadership within China, and leverage.
• "A Study on the Strategic Conflict between Mao Zedong and Stalin in the Early Period of Chinese People's Volunteer Army's entered the Korea War" (2023) — DOI: 10.29323/mchina.2023.3.97.121 — The first campaign on October 25, the introduction of the Soviet air force on November 1, and its expansion on November 6.
• "Reconsidering China's Decision to Enter the Korean War" (2023) — DOI: 10.1080/1547402x.2023.2268845 — The primary goal was Taiwan, securing Stalin's trust, with Sino-Soviet relations being the largest variable.
• "스탈린, 마오쩌둥의 지정학적 관점이 중국의 6·25전쟁 참전에 미친 영향 연구" (2021) — DOI: 10.21196/aprc.44.4.202102.003 — Tripwire, lips and teeth, and entering the war despite anticipating heavy casualties.
• "Far Short of a 'Glorious Victory': Revisiting China's Changing Strategies to Manage the Korean War" (2018) — DOI: 10.1080/1547402x.2018.1437505 — Chen Jian revisiting questions from over twenty years ago using new materials.
• "중화인민공화국 건국 전후 및 한국전쟁 초기, 중국의 한국전쟁과 참전에 대한 태도 변화와 배경" (2015) — DOI: 10.16912/tkhr.2015.03.225.231 — Western explanations of old vs. Chinese scholars since the 1980s, "no troops sent if the 38th parallel is not crossed," archives from July-August, notification of inability to deploy after Incheon, and the top priority being the consolidation of the regime.
• "북한의 남침에 대한 소련의 전략과 중국의 동의 배경" (2013) — KCI ART001775451 — China's promise of support was ideological, conditional, limited, and passive, direct troop deployment was out of the question, and Stalin's conception was securing a commitment of ground forces.
• "From the Cold War to the Hot War — The Korean War as seen from Shen Zhihua's 'The Cold War in Asia'" (2023) — DOI: 10.29323/mchina.2023.12.100.167 — Agreement with the ice-free port explanation while pointing out the lack of comparison between the West and the Far East, the UN Security Council absence on June 27, and the controversy over the August 27 Gottwald telegram.
• "중국의 한국전쟁 참전원인 연구: '국방선(國防線)'의 무혈확장" (2016) — DOI: 10.18206/kapdh.37.2.201602.5 — The Seventh Fleet, hope for early deployment and Stalin's opposition, notification of suspension after Incheon, decision on October 5, impossibility on October 12, Peng Dehuai and re-decision on October 13, the defense line, and no purpose of "expanding revolution."
• "Rethinking the Korean War" (2002) — DOI: 10.1515/9781400847617 — Introduction to Stueck's monograph, balancing international and internal factors.
• "중국의 한국전쟁 동의와 참전 결정 — '진영론'과 '안전론' 사이" (2020) — DOI: 10.29323/mchina.2020.9.87.1 — The February treaty, the consent stage based on camp logic, the entry stage based on security theory, and inability to oppose beyond agreement.
• "한국전쟁 중 중국군 참전에 대한 북·중·소 지도자의 협력과 갈등" (2016) — DOI: 10.17934/jmhs..141.201606.267 — Domestic political stability and national interests overriding ideology.
• "Mao's American strategy and the Korean War" (2021, Doctoral dissertation) — DOI: 10.7275/5drv-5m59 — Five interpretations, Goldstein's Greek tragedy, triggered by the blockade of the Taiwan Strait and the crossing of the 38th parallel.
• "중국의 한국전쟁 참전: 중국 대북정책의 역사적 형성과 지속" (2014) — DOI: 10.17331/kwp.2014.30.2.003 — Four variables, with the final variable being the instability of the Northeast region.
• "6·25전쟁 발발 전후 북한 게릴라의 활동과 성격" (2013) — DOI: 10.17934/jmhs..136.201312.95 — Planned by the North Korean Workers' Party faction with Soviet military advisers, regularized blitzkrieg operations, failure to consider the theory of a 200,000 popular uprising, absence of an uprising, and existing claims accepted as justification for purges.
• "1950년 1월 애치슨의 프레스클럽 연설과 하나의 전쟁 논리" (2002) — KCI ART000867927 — The core of the speech was China, South Korea being outside the defense perimeter but given top priority, Truman's non-intervention in Taiwan on January 5, and congressional controversy from January 10 to 11.
• "20世纪中国地缘战略與抗美援朝战争关係" (2007) — KCI ART002740479 — The Northeast as the base for revolutionary war and nation-building, criticizing theories of "passivity" and Cold War centrism.
• "탈식민과 냉전, 제3세계의 주체성 — 브루스 커밍스의 『한국전쟁의 기원』을 재평가하며" (2025) — DOI: 10.38080/crh.2025.05.151.314 — Revolutionary nationalism versus U.S. counterrevolutionary policy, minimizing internal diversity among Koreans and oversimplifying North Korean victimhood.
• "중국 무력개입의 문화심리요인: 한국전쟁 참전을 중심으로" (2008) — DOI: 10.18212/cccs.2008..12.016 — Socialist identity and anti-imperialist role influencing the decision and process of entering the war.
• "The Role of the Mongolian People's Republic in the Korean War" (2018) — DOI: 10.33526/ejks.20181801.97 — Russian documents released in the 1990s identifying the three leaders as the "main organizers," and inaccuracies in a 2016 declassified CIA document.