In recent months, scholars and strategists have questioned whether the United States would, could, or even should help Taiwan defend itself against an attack by the People’s Republic of China. The Cato Institute’s Doug Bandow claims that Taiwan is “not a serious security interest for America.” Bloomberg columnist Max Hastings insists that the “best chance of deflecting a Chinese assault [on Taiwan] is surely not military. […] The goal should be deterrence, with a focus on economic incentives for improved Chinese relations with the US.” Charles Glaser in Foreign Affairs suggests that “letting go of Taiwan” (among other retrenchments) may be needed to “reduce the odds of going to war.” As the 71st anniversary of the start of the Korean War in 1950 approaches, there are important lessons from the “Forgotten War” that have current relevance.
Of course, the PRC would prefer to absorb Taiwan using methods short of war if possible. Its subjugation of Hong Kong and intensifying attempts to bully the island democracy, however, have backfired and hardened Taiwanese resistance to unification (e.g., here, here, and here). For some time to come, China’s only chance of incorporating Taiwan will be through military conquest. Yet in the face of Beijing’s escalating threats, suggestions of reduced US support for Taiwan echo the mixed messages American leaders gave the Communist world on South Korea more than 70 years ago. George F. Kennan’s “strategic-political concept” represented this trend, premised on the idea that “the mainland of Asia was not strategically vital to the United States.”  Such calls for retrenchment may stem from a desire for peace and stability, but as the Korean War demonstrated, they can be highly provocative in practice.
After World War II, the United States wished to shift responsibility for South Korea’s defense to its own government in Seoul and almost completely withdrew from the peninsula. At the time, the South was a hotbed of Communist activity and tolerated the US troop presence grudgingly at best. Once the situation stabilized under the non-Communist government of Syngman Rhee, withdrawal no doubt seemed like a welcome option.  Yet when North Korea attacked the South on June 25, 1950, President Truman and his cabinet found they could not simply submit to Communist aggression. This withdrawal had fundamentally misaligned American actions and intent, giving the appearance of abandoning a government the United States actually meant to support. Although North Korea always intended to attack, abandoning Seoul as Pyongyang built up its forces gave North Korea a green light to initiate the Korean War, costing millions of lives and harming countless others. US retrenchment had in effect telegraphed a lack of commitment. Not only did this error weaken the US moral position, it also cost the United States far more in the end than a modicum of support ever would have.
Of course, primary responsibility for the war lies with North Korea and its PRC and Soviet enablers (despite Beijing’s historical revisionism), but as we discuss US support for Taiwan, we must relearn this lesson today: there is no substitute for firm, pragmatic commitment. As much as we may wish to set our responsibilities aside, we must not let a democratic US partner like Taiwan fall under PRC dictatorship. Shying away from such commitments, far from promoting peace, actually encourages war. At the time of the Korean War, some political figures placed special blame on US Secretary of State Dean Acheson’s less-than-supportive statements in his January 1950 speech to the National Press Club. More recently, Michael Green has suggested that it was a bipartisan lack of commitment in both word and deed that paved the way for the invasion by the North. 
In retrospect, and in full fairness to the benefits of retrenchment, pulling some forces back could have been an effective way to conserve American resources. Another way would have been to replace expensive military forces with more cost-effective means. Instances of such cost-saving measures have included: (1) The US transfer of one brigade out of South Korea in 2004, sending the unit where it was most needed while maintaining deterrence against the North; (2) the idea over the past decade or more of transitioning US efforts in Afghanistan from counterinsurgency to counterterrorism; and (3) the US first offset strategy of the 1950s, using nuclear weapons to bolster deterrence against the Soviet Union in place of large, expensive-to-maintain conventional forces.
This need to conserve resources holds true more than ever in the Indo-Pacific region today, including East Asia and Afghanistan. The resources of the United States and its allies are significant, but far from unlimited. This is particularly true in the context of Beijing’s prodigious and growing economy, which it uses to strengthen its military and other forces, as well as to maintain large-scale internal repression.
Good stewardship is a constant priority, but that cannot be allowed to muddle messages of deterrence to adversaries and assurance to allies. When word and action contradict actual intent, one is working at crossed purposes. Pulling nearly all US forces out and excluding Korea from the US “defensive perimeter” before 1950 left the unfortunate and misleading impression that the United States was less than willing to defend South Korea.
In the early 1950s, there was little to recommend the government in Seoul aside from its resistance to Communist rule. And yet, as social conditions changed and with the benefit of democratic influence, South Korea (like Germany and Japan before it) evolved into a strong, democratic ally. The democratic world benefitted immeasurably by supporting countries that at the time may have seemed less than promising. Unlike South Korea in 1950, Taiwan today is not a developing nation: it is a modern, prosperous democracy. While the United States has left the question of Taiwan’s legal status to the Taiwanese people themselves, it has consistently and clearly opposed any effort by the PRC to coerce unification.
Experts point to the difficulty of defending Taiwan against PRC attack. Despite this, the United States and its allies still possess a wide array of flexible means to do so. Some question their willingness to use force. Others even question whether Taiwan would defend itself. Of course, democratic societies are slow to anger, and the prospect of fighting a war absent an attack is unpopular.
Yet as we saw in the Korean War, this equation would change dramatically the moment the PRC seemed poised to destroy Taiwan’s democracy. At that point, the decision would be out of American hands. The United States would very likely have no feasible option other than to defend Taiwan against PRC attack. Any dictatorship that believes Americans are now ready to tolerate increasingly hostile acts makes a grave (although hardly unprecedented) error.
None of this is to say that the US commitment is unlimited. A war between two nuclear powers is no easy matter. That said, simply capitulating to Xi’s aggression is not an option either and US resistance is still inchoate. However, the democratic world is by no means alone or isolated. The injustice and gratuitousness of PRC actions invites opposition as countries small and large ask themselves whether Beijing would have any qualms about doing the same to them, one by one.
Has the American policy of strategic ambiguity then outlived its utility? Not necessarily. There is no need for any government to oppose (or support) Beijing’s “One-China Principle” directly, nor is it generally necessary for Taiwan to display its de facto independence in new ways, such as a declaration of independence or secession. But the United States must think twice before unilaterally weakening its commitments. No amount of propitiation can ever mollify Xi. It will only make him want more. Instead, Washington’s message to Beijing should be that Xi’s hostility is pushing Taiwan away and encouraging the rest of the world to resist him.
Beijing’s claims that Taiwan’s Tsai Administration favors “separatism” are a mere pretense. Taiwan’s opposition is a direct result of Beijing’s hostility. It cannot also be Beijing’s excuse for more hostility. Taipei is simply resisting PRC attacks on its duly elected government. It is the responsibility of the hostile actor to mend its ways.
Indeed, the People’s Republic, abusing the goodwill and support that the democratic world has lent it, has under Xi remade itself into the greatest possible threat, both to Taiwan and to the world: a genocidal, revanchist, totalitarian state bent on conquest. The appropriate response is for the world to decouple as thoroughly as possible—cutting off all trade and economic support for Xi’s inhuman program—and to arm itself against the invasion and destruction he is promising to unleash.
The democratic world poses no threat to China; quite the opposite, the PRC has benefited more than any other nation under its auspices. Some may believe that verbally cutting off Taiwan now will make conflict less likely, but the opposite is true. As we saw in the Korean War, it is a provocative act that incentivizes Beijing to strike. And by the time that happens, it will be too late to prevent a broader conflict. As Chamberlain learned at Munich, backing down from an enemy determined for war does not prevent conflict; it only prolongs it and makes it more horrible. Those who favor peace must now prepare to fight for it.
The main point: It is tempting for the US to back away from potentially difficult commitments like defending Taiwan, but as we learned in the Korean War, the US will have little choice if China attacks. It should therefore make itself as ready as possible.
 Paul J. Heer, Mr. X and the Pacific: George F. Kennan and American Policy in East Asia (Cornell University Press, 2018) p. 91.
 Ronald H. Spector, In the Ruins of Empire: The Japanese Surrender and the Battle for Postwar Asia (New York: Random House, 2007), pp. 138-166.
 Michael Green, By More Than Providence: Grand Strategy and American Power in the Asia Pacific Since 1783 (New York: Columbia University Press, 2017), p. 272-274 (Kindle edition).