by Ju-Hyun Park

75 years ago, in 1950, the People’s Republic of China made the fateful decision to deploy over a million soldiers of the Chinese People’s Volunteer Army in defense of the Democratic People’s Republic of Korea. This was not a straightforward decision at the time. There were those within the Communist Party of China (CPC) who questioned the wisdom¹ of committing the nascent republic to a foreign military operation against an enemy as powerful as the United States—particularly at a time when China remained politically divided and economically backward, having only established its state in 1949. 

To explain the necessity of the War to Resist U.S. Aggression and Aid Korea, Mao drew on an old Chinese proverb: “If the lips are gone, the teeth will be cold.” This statement reflected a straightforward geopolitical logic—one which the various rulers of China and Korea alike have discovered time and again. At times referred to as a “peninsular island”,² Korea’s position at the intersection of Russia, China, and Japan makes it a crucial pivot point in Northeast Asia. This geographical reality has shaped the historical development of the Korean nation and the wider region, and remains a crucial dimension of Sino-Korean relations in the contemporary era. 

While Mao’s observation most immediately concerned the question of mutual security, the phrase “lips and teeth” has taken on a life of its own to describe the closeness of the PRC and the Democratic People’s Republic of Korea (DPRK), which to this day is still the only country to enjoy a strategic alliance with China. By the time of the Korean War, the Korean and Chinese Revolutions were bonded by decades of joint struggle against imperialism. Driven from the peninsula by Japanese repression, a generation of Korean revolutionaries fought for China’s liberation during WWII (1931-1945) to achieve the international conditions necessary for the liberation of Korea and the world proletariat. 

After Korea’s liberation from Japan and the founding of the DPRK in 1948, 100,000 Koreans took up arms in China to defeat the Kuomintang.³ The DPRK and border Korean communities in Manchuria provided an essential rearguard to the People’s Liberation Army. When Chinese volunteers crossed the Yalu River in 1950, they were not only defending Chinese security or answering an abstract internationalist duty, but repaying the sacrifices of countless Koreans who had given their lives for China’s liberation.

Yet the phrase “lips and teeth” alone cannot describe either the contemporary or historical dynamism of the Sino-Korean relationship. Historically, Sino-Korean solidarity and friendship was forged in the crucible of Northeast Asia’s long encounter with capitalist expansion, from mercantilism to imperialism. Since the Korean War, the durability and depth of these bonds have been tested by shifting international conditions and the divergent paths each state has taken in response to them. Today, a rampaging Washington and an increasingly unstable liberal international order have once again produced the conditions for the DPRK and PRC to stand shoulder-to-shoulder—analyzing this development, not from the standpoint of slogans alone but as a new chapter in Northeast Asia’s long revolution, can provide the best understanding of the significance of this alliance and the possibilities it may open in the future.

From Feudalism to Socialism: Northeast Asia’s Long Revolution

Before Northeast Asia’s integration into capitalism, relations between various Korean and Chinese dynasties over millenia were marked by periods of collaboration, tributary domination, and even rivalry as peer competitors. As part of the Sinosphere, Korean kingdoms owed much of their development to economic and cultural exchanges with China, but it would be a mistake to view Korea’s historical role as only a recipient or a secondary actor. The exchange of ideas, technologies, and culture was not one-directional, and periods of dynastic decline and disorder in China usually coincided with the golden ages of Korean kingdoms. Just as much as the bounty of the continent benefitted Korea, its existence also depended on repelling a melange of invading forces from the continent, which at various times included Chinese dynasties. The peninsular island and the Middle Kingdom were thus bound together in a historical dialectic that can be observed across millennia. 

The gradual integration of Northeast Asia into the capitalist world over centuries would alter the former Sino-Korean dynamic, as the changing class composition of the region’s societies necessarily altered its politics. The earliest sign of this came in the Japanese invasions of Korea from 1592-1598, known as the Imjin Wars. For Japan, the invasions of Korea came at the end of more than a century of brutal warfare among competing daimyo, an era known as the Sengoku Period. The arrival of the Portuguese in the region would influence the trajectory of the Sengoku Period. From their colonial ports in Malacca (1511) and Macau (1557), the Portuguese established a mercantile monopoly over regional trade, and in the process introduced European firearms to Japan and stimulated its silver mining industry^.4 These factors would contribute to Japan’s unification, after which daimyo Toyotomi Hideyoshi set his sights on the conquest of Ming China by way of Korea. 

As in Western Europe, a mix of mercantile accumulation and feudal expansion drove territorial consolidation in Japan. Japanese pirates, or wokou, had plagued East Asia’s coasts for centuries,⁵ but the Japanese armada that set sail for Korea marked a qualitative shift in the archipelago’s regional role. For the first time, China was forced to intervene in Korea for the purpose of mutual security, rather than for conquest or to influence peninsular rivalries among competing Korean kingdoms. Though Japan was ultimately repelled, the Imjin Wars devastated Joseon Korea; a million people perished and hundreds of thousands were abducted by the invaders to be enslaved in Japan, or even sold as chattel to Europeans.⁶ The Ming Dynasty’s eventual collapse in 1644 was also in part the result of these wars.

The maturation of capitalism into imperialism, or the monopoly stage of capitalism, in the nineteenth century would usher in even greater horrors to the region. It was in this era that the capitalist powers finally amassed the strength to subjugate China in the Century of Humiliation, removing the Middle Kingdom as a bulwark against capital in the region. Japan and Korea, which both adopted policies of isolationism in the wake of the Imjin Wars, became much more exposed to the deprivations of an aggressively expanding capitalism. Japan responded with its own rigorous pursuit of capitalist development, launching itself into the ranks of the imperialist powers. 

The waning Joseon Dynasty of Korea eventually attempted to do the same, but was too late, and became swallowed up by inter-imperialist rivalry which ended in colonization by Japan. Once again, Korea became a battleground from which great historical changes that would alter the region’s future emerged. Japanese commercial imperialism in Korea inevitably challenged Qing tributary rights under the Sinocentric system. The resulting First Sino-Japanese War, chiefly fought in the peninsula, led to the surrender of Taiwan as a colony of Japan. With the Qing out of the equation, Japan then faced off against Tsarist Russia for control of Korea and Manchuria. Japanese victory in this war directly contributed to the revolution of 1905, striking a nail into the coffin of tsarism, which would be interred for good by the revolutions of 1917. As in the Imjin Wars, Japan saw in Korea a bridgehead to achieve the conquest of China, using the peninsula as a base for its invasion of Manchuria in 1931, which would set the stage for the Second Sino-Japanese War. 

Imperialism not only introduced new foreign actors into Northeast Asia—capitalist integration also altered the character of China and Korea’s existing tributary or feudal classes, and caused the development of a native bourgeoisie. The ruling classes of Qing China and Joseon Korea, characterized by a fusion of landlordism and control of the tributary bureaucracy, were first weakened by overt imperialist assault, and then enlisted into the exploitation of the toiling classes by capital. The masses of the peasantry, now at the mercy of the world capitalist market, were driven to proletarianization as they gained debt and lost land. As the feudal classes became integrated into imperialism, nascent bourgeois leadership emerged to fan the flames of national consciousness, but would prove futile or duplicitous over time. These historical transitions created the conditions for the communist movement to flourish in China and Korea. 

Though emerging from distinct national realities, China and Korea’s experiences of capitalist integration occurred as part of a singular historical movement of the extension of imperialism into Northeast Asia. The revolutions in these countries therefore developed coevally, conjoined by practical reality, geographic proximity, and historical affinity. Early Korean leaders of the armed independence struggle such as Hong Beom-Do and Yoon Hee-soon based themselves in Manchuria after facing defeat in the annexation of Korea. The 1911 Revolution in China and its leader Sun Yat-Sen held significant sway among Korea’s early independence movement;⁷ in turn, in 1919, China’s May 4th Movement, a high point of the New Culture Movement that would produce the future leaders of the CPC, took inspiration from Korea’s March 1st Movement of the same year. Bourgeois Korean nationalists affiliated with the government-in-exile based themselves out of Shanghai, allied with the Kuomintang; meanwhile, Korean and Chinese guerrillas, including Kim Il Sung, waged war against Japan from the jagged mountains of Manchuria. Koreans and Chinese did not make their revolutions separately, but together—and it was among the communists that this partnership ran deepest.

Communists from both nations found common cause in a joint struggle against imperialism and domestic reaction, shedding blood alongside each other. Korean revolutionaries, impeded from advancing the struggle on the peninsula by vicious colonial repression, turned to the revolution in China as a battleground to turn the tide against Japan. China’s revolution thus also became a Korean revolution. In Yan’an and beyond, figures such as Zheng Lucheng (Chong Ryul-song), Mu Chong, Ho Jong Suk, and Kim San dedicated themselves to China’s liberation as the path to realize Korea’s liberation. In Manchuria, Kim Il-Sung and countless other Koreans waged war alongside their Chinese comrades under the banner of the Northeast United Anti-Japanese Army. For a time, more than 90% of CPC cadres in Manchuria were Korean.⁸ As previously mentioned, once Korea was liberated in 1945 and the dictatorship of the proletariat realized in the founding of the DPRK in 1948, mass Korean participation in the final days of the Chinese Civil War helped ensure the victory of the CPC and the founding of the People’s Republic.

Sino-Korean solidarity in the Korean War was simply the latest chapter in a longer history of joint revolution. Once again, the struggle against imperialism in Korea had a lasting effect on the course of Northeast Asia’s historical destiny; the war never formally concluded, and a state of territorial fragmentation persists in both China and Korea to this day. The DPRK and PRC’s relationship since the signing of the 1953 Korean War Armistice therefore continues to be shaped by the conditions of Northeast Asia’s long revolution. 

Forks in the Road

The great sacrifices of the Chinese People’s Volunteers have never been forgotten by the DPRK. Still, the Sino-Korean relationship has continuously evolved, and at times, the lips and teeth have been at odds. The Sino-Soviet Split,⁹ and later, the Reform and Opening Up Era precipitated various diplomatic and political conflicts between the two states. 

Undoubtedly, the relationship reached its nadir in the 1990s, when the fall of the Soviet Union left the DPRK without its largest trading partner, and more vulnerable than ever to U.S. sanctions. In 1994 and 1995, calamitous once-in-a-century floods devastated its agricultural base and led to a period of famine known as the Arduous March.¹⁰ At the time, China’s friendship with the DPRK was restrained, and socialist Korea was largely abandoned to face its crisis alone. 

While the DPRK survived the Arduous March, relations with the PRC remained strained for some time, and are still not without their contradictions. Diplomatically, the PRC continued to support and enforce UN Security Council sanctions on the DPRK until 2019, when it proposed partial reductions of sanctions in a joint resolution with Russia.¹¹ The DPRK’s nuclear weapons program has also, at times, been another source of tensions.¹³ Acknowledging these contradictions is crucial to understanding the historical ambit of the PRC-DPRK relationship; simultaneously, they should not be overemphasized, or reduced to simple ideological explanations. These contradictions arose from material differences between the two states’ respective positions in the contemporary world-system, as divergent conditions compelled the two states to pursue divergent interests in accordance with divergent strategies.

During Reform, China reintegrated into the capitalist world-system in order to massively develop its own productive forces—albeit without surrendering socialist command of politics. This changed the country’s strategic calculus regarding many of its foreign relations, including with the DPRK. Whereas the DPRK underwent a generation of crushing ostracization and vilification by the U.S.-dominated international order, the PRC’s economic rise became contingent upon its cooperation within that very order. Divergent strategies between the two states are therefore a reflection of divergent interests and conditions. 

A common destiny?

Yet today, a new dispensation is forming. China’s rise has encountered its opposite in heightened U.S. belligerence in East Asia and around the world. This growing aggression takes the form of expanded militarization and the formation of a new U.S.-led military bloc in the region, composed of constituent alliances such as AUKUS (Australia-UK-U.S.), JAKUS (Japan-Republic of Korea-U.S.), and the SQUAD (India, Japan, Philippines, Australia, U.S.). The 2026 National Defense Authorization Act, which is being debated in the U.S. Senate at the time of this author’s writing, includes plans for the creation of “the Partnership”—a vaguely defined defense industrial free trade consortium including Japan, the Republic of Korea (ROK), Australia, the Philippines, India, and New Zealand.¹³ The growth of new alliances is also accompanied by the acceleration of U.S.-led military exercises, particularly but not exclusively in Korea, where according to independent journalist Jang Chang-jun,¹⁴ U.S. Forces Korea (USFK) has conducted 200 days of military drills in 2023 and 275 days of military drills in 2024—with a new record expected to be broken in 2025.

Plagued by military overreach and the tendency of the rate of profit to fall, Washington now seeks to internationalize military Keynesianism by pressuring its vassals to open the spigots of military spending, including Japan and the ROK. The DPRK’s recent comprehensive strategic partnership with Russia must be viewed in this light. The fault lines of the old Cold War, which never truly ended in Northeast Asia, are now deepening as a consequence of this New Cold War. 

Today, Washington sees little meaningful distinction between the DPRK and the PRC as antagonists. In a study published in May 2025,¹⁵ the Atlantic Council branded the two states “a rising nuclear double-threat,” arguing that the U.S. must prepare for “simultaneous” conflict with both—even if it would mean limited nuclear war. U.S. military leadership has already come to see the vast “Indo-Pacific” as a singular battlefront, one which pivots on the Korean Peninsula. Recent revelations from South Korean media found USFK using an inverted map¹⁶ of the region placing Korea in the center, with lines of distance drawn to the major cities and capitals of Russia, China, Taiwan, the Philippines, and Vietnam. In a keynote address to the U.S. Army Land Forces Pacific Symposium in May 2025, General Xavier Brunson, commander of USFK, spelled out the value of Korea to imperialism in explicit terms: 

“What immediately stood out to me as I looked at the map was the position of the Korean Peninsula, and the fact that it’s on the Asian continent, has a sizable U.S. force posture, is inside the first island chain and is the closest allied presence to Beijing….At night from a satellite image, the Republic of Korea looks like an island or like a fixed aircraft carrier floating in the water between Japan and mainland China.”¹⁷

Beyond his brutishly utilitarian description of Korea as an “aircraft carrier,” Brunson’s comments also signalled a new vision for the US-ROK alliance. In a push to “modernize” the alliance, Washington now seeks to redefine USFK’s mission from primarily containing the DPRK to containing China, breaking with the original terms of the US-ROK Mutual Defense Treaty and other core documents governing the U.S. occupation of Korea. This pivot would allow for USFK to be flexibly deployed beyond the Korean peninsula, and thereby make Korea into a battleground for U.S.-China war by default. Once again, imperialism seeks the subjugation of China by way of the Korean Peninsula—consequently, the DPRK and PRC’s strategic interests now align more closely than at any time since the fall of the Soviet Union, and a revitalization of revolutionary solidarity and fraternity is underway.

At the recent 80th Anniversary of the Victory of the Chinese People’s War of Resistance Against Japanese Aggression and the World Anti-Fascist War, Kim Jong Un was given pride of place in the celebrations, and exchanged important statements of friendship with Xi Jinping. In his statement to Kim, Xi called for greater “friendly cooperation”, not just between the two countries but between the CPC and the Workers’ Party of Korea, stressing the fields of security, economics, and governance to enhance “our socialist causes.” It has yet to be seen how the relationship will continue to evolve. While the imperialist intelligentsia is given to braying about the existence of a China-Russia-DPRK bloc, the real formation of such an alliance is still in development. As U.S. hostility in the region intensifies, China and the DPRK will face mounting existential pressures to find strategic unity. Contradictions and challenges will no doubt persist, but if the history of the Chinese and Korean Revolutions offers anything to the present, it is that the destinies of these two great historical processes are shared, and can only be strengthened through collaboration. Just as lips and teeth must coordinate to speak, so too will the revolutionary forces of Northeast Asia seek unity to articulate a common future of peace and prosperity into the annals of history.

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¹“Speech to the Cadres of the Chinese People’s Volunteers,” Peng Dehuai, Peng Dehuai [unshi Wenxuan (Beijing, I988), pp. 320-26. Uncertain partners pg.284-289, https://www.commonprogram.science/documents/Pend%20Dehuai%20speech.pdf. 

²Cumings, Bruce. “Korea’s Place in the Sun: A Modern History.” The SHAFR Guide Online, October 2, 2017, https://doi.org/10.1163/2468-1733_shafr_sim200070107.

³Donggil Kim, “Prelude to War? The Repatriation of Koreans from the Chinese PLA, 1949-1950,” Cold War History, Vol. 12, No. 2 (2010), 227-244. 

⁴Flynn, Dennis O., et al. “Born With a ‘Silver Spoon’: The Origin of World Trade in 1571.” Journal of World History, vol. 6, no. 2, University of Hawai‘i Press, 1995.

⁵Though classically attested to as Japanese pirates, contemporary scholars believe the wokou were motley crews of varying origins.

⁶De Sousa, Lúcio. The Portuguese Slave Trade in Early Modern Japan Merchants, Jesuits and Japanese, Chinese, and Korean Slaves. 2018.

⁷Min, Tu-Ki. “Sun Yat-sen in Korea: Korean View of Sun Yat-sen’s Idea and Activities in 1920s.” 동아문화, vol. 30, December 1992, pp. 225–41.

⁸ Hongkoo Han,“Wounded Nationalism: The Minsaengdan Incident and Kim Il Sung in Eastern Manchuria” (Ph.D. diss., University of Washington,) 10.

⁹The DPRK adopted a non-aligned position in the Sino-Soviet Split, and increasingly turned to the Non-Aligned Movement in the 1970s and 1980s.

¹⁰Meredith Woo-Cumings. The Political Ecology of Famine: The North Korean Catastrophe and Its Lessons. 2002, www.adb.org/sites/default/files/publication/157182/adbi-rp31.pdf.

¹¹North Korea, China, Russia Converge Positions | Arms Control Association. www.armscontrol.org/act/2020-01/news/north-korea-china-russia-converge-positions. 

¹²Slavney, Natalia. “Quick Take: North Korea Jabs at China in Reaction to Trilateral Summit – 38 North: Informed Analysis of North Korea.” 38 North, May 28, 2024, www.38north.org/2024/05/quick-take-north-korea-jabs-at-china-in-reaction-to-trilateral-summit.

¹³“Text – S.2296 – 119th Congress (2025-2026): National Defense Authorization Act for Fiscal Year 2026.” Congress.gov, Library of Congress, September 11, 2025, https://www.congress.gov/bill/119th-congress/senate-bill/2296/text. 

¹⁴“[신년특집]2024년 한미•한미일 군사 연습의 실체.” 현장언론 민플러스, January 29, 2025, www.minplusnews.com/news/articleView.html?idxno=15777. 

¹⁵Aroh. “A Rising Nuclear Double-threat in East Asia: Insights From Our Guardian Tiger I and II Tabletop Exercises – Atlantic Council.” Atlantic Council, May 12, 2025, www.atlanticcouncil.org/in-depth-research-reports/report/a-rising-nuclear-double-threat-in-east-asia-insights-from-our-guardian-tiger-i-and-ii-tabletop-exercises. 

¹⁶Hyo-Jin, Lee, and Bahk Eun-Ji. “Washington May Weigh Shake-ups of Top US Commanders in South Korea, Japan.” The Korea Times, July 9, 2025, www.koreatimes.co.kr/southkorea/defense/20250710/washington-may-weigh-shake-ups-of-top-us-commanders-in-south-korea-japan. 

¹⁷“US Forces Korea Leader Says His Troops Deter China, Guard ‘Freedom’s Front Yard.’” Stars and Stripes, May 16, 2025, www.stripes.com/branches/army/2025-05-16/brunson-south-korea-china-lanpac-17807125.html. 

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Ju-Hyun Park is a writer and organizer with Nodutdol for Korean Community Development, an anti-imperialist Korean diaspora organization based in the U.S. which coordinates the U.S. Out of Korea campaign. Ju-Hyun’s writing on Korea and U.S. imperialism in the Pacific has appeared in Public Radio International, The New Inquiry, Funambulist, People’s Dispatch, and other publications. Ju-Hyun is the Web Editor at BreakThrough News.