Why a US-North Korea Summit Could Hollow Out Seoul's Security

The Summit That Skips Seoul

Donald Trump is pressing his team to lock in a second meeting with Kim Jong Un by November. The venue? The APEC summit in Shenzhen, China — a location that immediately signals how much the calculus has shifted. This is no longer a bilateral conversation happening on neutral ground or in Pyongyang. It is being woven into a broader Asian architecture where Beijing sits at the table and Seoul may not.

Trump has already taken steps to signal his intentions. In mid-August, he ordered an emergency reduction of Ulchi Freedom Shield, the annual joint military exercise between the United States and South Korea — the same exercise that serves as the primary visible demonstration of extended deterrence on the peninsula. He has publicly praised his relationship with Kim, calling him someone who consistently shows him respect and with whom he has had multiple meetings. The language is deliberately intimate, almost transactional. It is the language of a dealmaker, not an alliance manager.

North Korea’s response has been characteristically ambiguous. The regime neither confirmed nor denied reports that Kim accepted a summit invitation. Kim Yo Jong dismissed the reports as something she knew nothing about, then separately acknowledged that her brother holds positive personal memories of Trump. The message is calibrated: enough ambiguity to keep Washington guessing, enough warmth to keep the door open.

Seoul Is Already Left Out

The problem for South Korea is not hypothetical. The current inter-Korean relationship is governed by what Pyongyang calls its two hostile states doctrine — the formal position that the South and North are not co-nationals but rival sovereign entities at war. This framework was reinforced through repeated missile tests, rhetorical escalation, and the outright severing of diplomatic channels that defined the early years of the previous administration’s engagement strategy.

President Lee Jae-myung’s administration has attempted to position itself as a facilitator, even volunteering as a mediator between Washington and Pyongyang. The efforts have produced nothing. There is simply no seat at the table for Seoul when the dynamics are structured as a direct Trump-Kim exchange. The precedent was established in 2018-2019 and it has not changed. These summits were designed to be personal, top-down, and deliberately outside institutional channels — precisely the configuration that excludes allied partners by design.

The Nuclear Question Has Disappeared

Perhaps the most consequential shift is what Trump is refusing to say. During his first term, every summit — Singapore, Hanoi, the failed second attempt — operated under the stated objective of North Korean denuclearization. That language has now been erased. Trump has explicitly told reporters he does not want to discuss denuclearization. The US National Defense Strategy has removed North Korea denuclearization as an explicit goal. The administration is effectively decoupling engagement from disarmament.

This matters because it changes what a summit would accomplish. If there is no substantive agenda around denuclearization, then what is being negotiated? The most likely answer is some version of security reassurance — implicit or explicit guarantees about troop posture, exercise scale, or the scope of extended deterrence — traded for nothing more than continued diplomatic contact.

That trade-off is deeply problematic for Seoul. North Korea’s nuclear arsenal has expanded significantly since 2019. The regime now possesses warheads capable of reaching the US mainland. Its involvement in the Russia-Ukraine war has provided additional military and economic reinforcement that strengthens its strategic position. The threat environment is worse, not better. Yet the US response is moving toward accommodation rather than reinforcement.

The Deterrence Gap

American policymakers are already voicing concern. Jennifer Lind and Daryl Press, both prominent scholars of alliance politics, have published proposals in Foreign Affairs suggesting short-term tactical nuclear deployments on the Korean peninsula and, for South Korea, the long-term development of an independent nuclear deterrent. That such proposals are being seriously discussed in mainstream strategic journals is itself a diagnostic. It indicates that the existing extended deterrence framework is perceived as insufficient or unreliable.

The core risk is that a US-North Korea summit conducted without meaningful South Korean involvement creates a perception gap that no amount of diplomatic reassurance can fill. If Seoul believes Washington is willing to negotiate security arrangements with Pyongyang without Seoul at the table, then the credibility of the alliance erodes regardless of what is formally agreed. Extended deterrence depends on perceived commitment as much as actual capability.

Fred Fleitz, a senior adviser on Trump’s foreign policy team, has offered a straightforward suggestion: Trump should meet with President Lee before meeting with Kim. Coordinate agendas. Include Seoul. It is a small structural adjustment that would carry enormous symbolic weight and substantive consequences for how the negotiations are framed.

What Happens Next

A summit in Shenzhen would be the first US-North Korea meeting held on Chinese soil, which adds another layer of complexity. Beijing would be positioning itself not merely as a host but as a gatekeeper to the most consequential security dialogue in East Asia. That dynamic further marginalizes Seoul, whose diplomatic space in the region is already compressed between American alliance obligations and Chinese economic leverage.

The alternative — no summit, continued ambiguity — carries its own risks. It keeps the door open for future escalation while offering no diplomatic off-ramp. But the current trajectory points toward a narrow pathway: a personal meeting between two leaders who have a track record of unilateral decision-making, held in a venue that signals the geopolitical realignment underway, with an ally that has spent months trying to insert itself into the conversation and failing.

The window for Seoul to shape this process is narrow. If Trump proceeds with a China-hosted summit without prior consultation with the South Korean government, the damage to alliance credibility will be immediate and difficult to reverse. If he follows Fleitz’s advice and coordinates first, the result could still fall short of what Seoul needs — but at least the architecture would include the ally rather than bypassing it entirely.

The stakes extend beyond the peninsula. How the United States manages extended deterrence in East Asia during this transitional period will signal to Tokyo, Seoul, and other allies whether the security guarantee is conditional or structural. A summit that treats South Korea as an afterthought will be read across the region as the opening chapter of a broader retreat — or at minimum, a recalibration that prioritizes deal-making over alliance management.

Neither outcome serves American strategic interests. But both are possible if the default assumption remains that Washington can negotiate security arrangements for the Korean peninsula without its primary partner.