South Koreans are worried about the three-body problem. Not the astrophysical phenomenon featured in the popular science fiction novel by Liu Cixin; rather, it’s the geopolitical phenomenon that links China, Taiwan and North Korea. Because of the relationships among these three governments, a war in the Taiwan Strait could cause a military conflict on the Korean Peninsula.
If the USA intervened to defend Taiwan from an attempted Chinese takeover, Pyongyang, possibly at Beijing’s request, might carry out aggression against the Republic of Korea (ROK) at a time when South Koreans feel relatively vulnerable because of US preoccupation with the battle some 1,500 kilometers to the south.
From President Yoon Suk Yeol to analysts in both academic and government, South Koreans have expressed anxiety about an opportunistic North Korean attack.
There is no question that a Taiwan Strait war would be a calamity for the region, including South Korea. The economic effects alone would severe, with military operations in the East China Sea disrupting the trade that the ROK heavily relies on. Moreover, Seoul would be politically squeezed between its ally the United States and its main trading partner and well-armed neighbor China.
The US military would likely use its ROK-based strike aircraft in the fight against China, leading Beijing to consider missile attacks that would fall inside South Korean territory. Seoul’s difficult challenge would be to find a path that both avoided outright war with China and spared Seoul from US condemnation as a useless ally.
The ROK would be in danger of suffering serious long-term damage to its prosperity, via the collapse of economic cooperation with China, and to its security, by creating a hostile relationship with China and possibly ending the alliance with the USA.
That China and the Democratic People’s Republic of Korea (DPRK) might coordinate simultaneous attacks is plausible. It is safe to assume PRC planners have at least thought about it. For what it’s worth, the two countries are still treaty allies, although the efficacy of that alliance has proven questionable over the years.
The PRC is not only in a near-panic about what it perceives as the USA encouraging Taiwan independence as a means of “containing” China; it also views with alarm increased South Korean willingness under the Yoon government to support an anti-China US agenda.
Beijing’s wish is that the ROK government would block the United States from using South Korea as a base or staging area for military operations in the Taiwan Strait. But Chinese analysts no longer believe that is likely.
Pyongyang, as well, sees linkage between the China-Taiwan and DPRK-ROK conflicts. The North Korean government supports the PRC position that China owns Taiwan and that the cross-Strait issue is a Chinese “internal affair.”
North Korean Vice Foreign Affairs Minister Pak Myong-ho combined the two issues in a 2021 statement. The USA, he said, tries to block national unification in both China and Korea as a way to “stifle our country and China, both socialist countries, in order to hold its supremacy.” Pak said US forces “being concentrated near Taiwan” to pressure China “can be committed to a military operation targeting the DPRK at any time.”
Pak also disparaged the “assertion” that China and the DPRK would coordinate to “cause military tension in Taiwan and on the Korean Peninsula.” He compared this to “a guilty party filing the suit first.” Somehow this seems less like a reassurance that China and the DPRK would never do this than an acknowledgment that it sounds like a good idea.
Nevertheless, South Korean worries about the particular scenario of North Korea taking advantage of a Taiwan Strait conflict are unnecessary. The ROK could take in stride any likely DPRK actions.
To begin with, the DPRK’s policy toward South Korea follows Pyongyang’s own considerations and timeline. It is far from certain that an attack timed to match what China was doing in the Taiwan Strait would align with Pyongyang’s agenda and plans at that time. The North Koreans would be on guard against being exploited for the PRC self-interest.
An obvious possible DPRK “provocation” would be a test nuclear explosion or an intercontinental ballistic missile test flight. Both of these kinds of tests, however, have become routine. They will occur regularly even if the United States is not distracted by another war, and they require no military response or adjustment by US or ROK forces – although sometimes Seoul or Washington will answer with a show of force as a morale booster for the South Korean public.
The North Korean government might carry out some form of small-scale lethal attack. This would not be a shock to South Koreans, who suffered many such attacks prior to the hiatus that has been in place since 2010.
Examples might include
- a naval skirmish near the disputed west sea maritime border – see reconstruction above of what South Korea said was a midget submarine attack on its corvette ROKS Chonan on March 25, 2010, in which 46 sailors were lost;
- North Korean artillery shelling of an ROK-held island;
- a commando raid; or
- a rocket strike against a sparsely populated part of South Korea.
Although tragic for the families who lose loved ones, these attacks cause no significant harm to overall national security.
More serious would be a large-scale North Korean attack, such as bombardment of a metropolitan area or military base. Whether it occurred during a Taiwan Strait war or not, such an attack would evoke major ROK military retaliation, probably escalating to all-out war and the consequent extinction of the Kim regime. For this reason Pyongyang is highly unlikely to choose this option.
An attempted DPRK invasion of the South is equally unlikely. Although the ROK armed forces could almost certainly defeat it by themselves, they would have help from the ROK-based US ground troops who would remain on the Peninsula because most of the American forces fighting in the Taiwan Strait would be ships and aircraft.
Furthermore, either a small or a large North Korean attack would strengthen the rationale for keeping US forces on the Peninsula to deter the DPRK rather than sending them to fight in the Taiwan Strait. This would mollify the South Korean concern about the Americans abandoning them at a dangerous time.
The most audacious possible DPRK action, the use of a nuclear weapon to kill South Koreans (or Japanese), is out of the question for Pyongyang, even if the United States is simultaneously fighting to protect Taiwan.
Although governments are typically careful not to specify in advance how they would respond to particular hypothetical situations, the US 2022 Nuclear Posture Review says ,with extraordinary bluntness, “There is no scenario in which the Kim regime could employ nuclear weapons and survive.”
The US may run low on conventional weapons stocks, but it has plenty of nuclear warheads.
Superficially, Seoul’s alliance with the United States seems to be the root cause of the ROK’s three body problem. South Koreans fear they face both of the possible downsides of an alliance relationship: being dragged into someone else’s war, and being abandoned by one’s partner in a time of peril.
Beijing and Pyongyang, however, deserve blame for their willingness to use violence to impose their will on neighboring countries. And in the main, if war breaks out in the Taiwan Strait, the ROK’s problem will be China, not North Korea.
Denny Roy is a senior fellow at the East-West Center in Honolulu.