South Korea’s options in post-America Asia

Hugh White’s recent essay in The Quarterly argues that Australia should be preparing now for the departure of the U.S. He notes “it is futile for Australia to frame its defence around U.S. deterrence of China when America itself is not serious about it.” His essay is understandably focused on Australia, but much of what he says applies equally to South Korea. Should South Korea be preparing now for the departure of the U.S.?

White argues that the United States will retreat from Asia not because it lacks military strength, but because political will is weakening as it becomes clear that it no longer makes strategic sense to sustain regional dominance. In past eras—during the First World War, the Second World War, and the Cold War—it made sense for the U.S. to project power across the globe to prevent any single state from dominating Eurasia. These conditions no longer apply.

Today’s world is multipolar, with power in Eurasia distributed among Europe, Russia, China, and India. Nuclear war is the only real threat to the U.S. and it will not risk this for Taiwan, South Korea, the Philippines or Australia. Simply, the U.S. no longer needs to impose order, and will instead act as an offshore balancer—intervening when necessary to prevent hegemony, but otherwise letting the regional powers constrain one another.

Applied to Korea, the essay suggests Seoul is at a strategic turning point. The longstanding reliance on the U.S. as a security guarantor is becoming increasingly uncertain as America reassesses its global role and retreats from regions where it no longer sees hegemonic necessity.

While the U.S. may remain present in a limited capacity, its commitment to extended deterrence will weaken, forcing Seoul to reconsider the viability of its dependency. This will be especially pressing as China consolidates regional influence and as U.S. domestic politics make sustained foreign commitments more erratic. South Korea, positioned at the fault line of great power rivalry, can no longer assume the credibility of U.S. protection is guaranteed.

White goes further to argue that the Korean Peninsula may ultimately be the precipitant that pushes America’s departure. North Korea’s development of intercontinental nuclear capabilities is a direct threat to the U.S. South Korea is increasingly less confident of U.S. extended deterrence. This erosion of trust has led to increasingly serious discussions in Seoul about pursuing an independent nuclear weapons program (see below).

If South Korea does take steps toward nuclearization, it could profoundly shake the foundations of the U.S.–Korea alliance. The fallout would not only weaken ties with Seoul but also raise questions about America’s broader position in Asia, including its alliances with Japan. As White notes, the Korean Peninsula may be “the final nudge that brings the American era in Asia to a close.”

Where does this leave South Korea today? Should South Korea be preparing now for the departure of the U.S.?

Thinking about South Korea’s strategic futures is fraught with uncertainty. It is a region that encompasses all of Donald Rumsfeld’s known knowns, known unknowns, and unknown unkowns, and any combination there of. It is also a a topic that is rarely debated openly in public. Foreign policy and strategic debate was traditionally seen as the concern of a small epistemic community and a coterie of close advisors, and questioning long-standing conventions, such as the U.S. alliance, is unheard of outside the extreme left and right.

There is no chance that the question whether South Korea should be preparing now for the departure of the U.S. would be asked in mainstream political debate. This does not mean that it is not asked in the epistemic community. Some are seriously considering South Korea’s position in a post-America Asia.

South Korea’s strategists settle around three broad approaches: securing U.S. long-term commitment; acquiescing to China’s regional dominance; and achieving armed independence (there are other less common options that will be discussed in coming weeks). None of these approaches are easy and all involve nuclear weapons in one way or another.

The first approach, securing the long-term commitment of the United States remains the default approach for many South Korean strategists. This path is grounded in the historical success of the U.S.–ROK alliance, which has deterred North Korean aggression and provided a security umbrella for South Korea’s economic rise. If there’s one thing politicians love, it’s selling an uncertain future based on narratives used successfully in the past.

Yet this strategy faces growing challenges. As White notes, the credibility of extended deterrence is increasingly questioned, particularly as North Korea’s ICBM capabilities introduce doubt about whether Washington would risk its own cities to defend Seoul. The political will in the U.S. to sustain costly overseas commitments is also eroding, and future administrations may be more transactional or isolationist. To shore up American commitment, Seoul will need to seek greater interoperability, missile defense cooperation, or even shared control over nuclear assets—moves that inevitably deepen South Korea’s entanglement in U.S. efforts to deter China.

The second approach, acquiescing to China’s regional dominance, is the least publicly discussed but most often quietly acknowledged in serious circles as a possible long-term reality. As China becomes the dominant economic partner for much of Asia and expands its military and technological influence, South Korea will eventually face pressure to align more closely with Beijing. For some, it is a simple return to a long history of dealing with China. It would involve recalibrating its strategic posture to avoid provoking China, minimizing military integration with the U.S., and remaining neutral in conflicts like a Taiwan crisis.

Some on the extreme left are so confident of this, that they see China as the path to Korea’s ultimate unification. Those on the extreme right are of course vehemently opposed to this approach and argue that it would result in a loss of democratic freedoms and human rights (which is pretty rich given their support for Yoon’s feckless grab for authoritarian control six months ago).

Such a path would also not insulate South Korea from nuclear dynamics. It would place the country in a vulnerable position, reliant on China’s responsible management of the region and its capacity to restrain and control Pyongyang. Nuclear blackmail would conceivably still be an issue. There would also be the temptation to replace the loss of U.S. nuclear assurances with the quiet pursuit of its own latent capabilities and/or the promotion of greater ambiguity on capacity. This leads to the third approach.

The third approach—achieving armed independence—entails the most radical departure from existing policy. It reflects a growing sentiment in South Korea that true security can only come from self-reliance. A sentiment that is entrenched in Korean (both North and South) understanding of the world dating back to Korea’s enlightenment period.

Today, this understandably includes nuclear weapons. Proponents argue that an independent deterrent would restore credibility, reduce dependency on unreliable allies, and allow Seoul to navigate a more multipolar Asia with greater confidence.

However, this path carries enormous diplomatic, economic, and strategic risks. It would likely rupture the alliance with the United States (although this is open to conjecture and debate), provoke strong reactions from China and Japan, and invite international sanctions. Still, the mere existence of this option in mainstream debate underscores how deeply nuclear considerations now pervade South Korea’s strategic discourse.

Whether seeking protection, adaptation, or independence, every viable path forward confronts the same grim reality: nuclear weapons are no longer a background issue—they are central to South Korea’s future.

Ultimately, what White’s argument exposes is not just the unreliability of American commitment, but the danger of strategic passivity in an age of geopolitical flux. South Korea cannot afford to wait for a definitive signal from Washington before recalibrating its national security posture.

The writing is already on the wall: American strategic attention is shifting, deterrence guarantees are fraying, and future administrations will prioritize domestic interests or entirely recast global obligations. Pretending otherwise only delays necessary debate. It is not alarmist but prudent for South Korea to prepare now for a post-American Asia—while options still exist and consequences can still be shaped.

The United States may not leave tomorrow, or next year, but when it does, the cost of not having prepared will be borne entirely by Seoul.

[For reference, see Hugh White. “Hard New World: Our Post-American Future” in Quarterly Essay No.98 (p. 82). Schwartz Books Pty. Ltd.]