Three years ago I outlined what the contours of a war between China and the United States might look like. Although disagreements between Washington and Beijing over Taiwan and the South China Sea have hardly subsided, it increasingly appears that affairs on the Korean Peninsula would provide the spark for conflict. If the tense situation in Korea led to war between the United States and China, how would the conflict start? Who would have the advantage? And how would it end?
How it Would Start
War between North Korea, or the DPRK, and America is more likely to ignite a war between China and the U.S. than vice versa, although it’s not incomprehensible that Pyongyang might take advantage of U.S. distraction with China to make a move against South Korea. But if we assume the former, it would change the military situation at the beginning of the U.S.-China conflict. Whereas in most scenarios a war happens according to Beijing’s timetable, and consequently to Beijing’s advantage, if North Korea triggers a conflict China may be forced into a fight that it does not want and is not fully prepared for. At the very least, it would allow U.S. forces to fully mobilize in expectation of fighting against China. Even if the Chinese were allowed to launch the first blow, U.S. forces would be on high alert, tracking Chinese moves and capable of responding immediately. The experience of November 1950 , in which China was allowed to launch a surprise attack, would surely be at the top of the minds of U.S. commanders.
China could decide to intervene in a new Korean War under two circumstances; first, if it believed that the U.S.-ROK coalition was on the verge of destroying the DPRK (as was the case in 1950), and second, if it believed that the DPRK was winning and that Chinese intervention could preempt U.S. escalation. If the former case, China’s war objectives would be to prevent the destruction of the DPRK, and to prevent the DPRK from unleashing its nuclear arsenal. In the latter, the objective would be the opposite; to secure North Korean gains (whether these amounted to the entire Korean Peninsula or not), and to eliminate any temptation on the U.S. part to escalate to nuclear weapons. In either case, U.S. and ROK planners would pay careful attention to Chinese maneuvers, and both countries would have fully mobilized for war.
Neither China nor North Korea have a lot of friends around the world. Still, both would likely enjoy benevolent neutrality from Russia, which would help significantly in keeping the militaries of both supplied with fuel, spare parts and ammunition.
The rest of the world would likely support the United States and the ROK to various degrees, less if the U.S .started the war, more if the DPRK started it. China would undoubtedly worry about its southwestern flank, but India is unlikely to intervene in any conflict that does not directly involve its interests. America’s European and Pacific allies would offer rhetorical and potentially some minor military support.
Japan’s participation would be the biggest question mark. Tokyo regards both North Korea and the growth of Chinese military power as key national security threats. Japan might well come under attack from North Korea during intra-Korean hostilities. At the very least, Japan would offer basing and support to the United States and (more quietly) to the ROK. But if Tokyo perceived that a Chinese-North Korean axis might win (as apart from merely preserving a rump DPRK), then Tokyo might well intervene on the U.S. side in a meaningful way. The combination of Tokyo’s military, financial, and economic might could significantly affect the course of the conflict.
The Course of Combat
On balance, South Korea is considerably more powerful than North Korea. While North Korea’s forces can cause enormous damage to South Korea in a conventional conflict, they cannot hope to destroy the Republic of Korea, or ROK, on their own. Attacks in depth against North Korean communications and logistics would make it difficult for the North Korean Army, or KPA, to maneuver. And in the early days of the conflict, South Korean and American airpower would utterly control the sky.
Chinese intervention could change this equation. War between the Koreas would create a problem for the U.S. by introducing the necessity to supply and maintain large scale land forces on the Korean Peninsula. Unleashed against South Korea, Chinese ballistic and land-attack cruise missiles could wreak havoc on U.S. and ROK military installations. Missiles would destroy Coalition aircraft on the ground, and reduce airfield readiness. Attacks on staging and logistics areas would give U.S. and ROK forces a taste of the same problems they had dished out to the North Koreans. US naval forces and installations would also come under attack.