Modernization Without Theory: The U.S.-ROK Alliance in an Age of Strategic Incoherence
Updated: Jul 7
Mr. Michael Schiffer | Senior Fellow, Center for American Progress
The architecture of American alliances in Northeast Asia was built for a world that no longer exists. The hub-and-spoke system that anchored U.S. security relationships in the Indo-Pacific was designed during the Cold War to manage a bipolar confrontation between two superpowers with functioning bureaucracies, rough nuclear parity, and a shared interest in avoiding direct conflict. The post-Cold War refinements assumed American hegemonic primacy—a unipolar moment in which the question was not whether U.S. power could underwrite the system, but how far its guarantees should extend. Both assumptions are now obsolete.
The world in which U.S. alliances must operate today is defined by great-power competition among multiple actors with asymmetric capabilities and misaligned interests, the accelerating diffusion of advanced technology, and a United States whose domestic politics have placed the foundational premises of alliance leadership under sustained pressure. Whether the system built for prior worlds can be transformed in time—and whether Washington and its allies can navigate that transformation together before the strategic environment makes the choice for them—is the question that animates every serious alliance debate now underway.
Although the competition is stiff, perhaps nowhere is this tension playing out more acutely than on the Korean Peninsula, where the consequences of mismanaging this period of alliance transformation to create new structures and new capabilities fit for the new realities of a new world are pressing, and where the need to be able to “fight tonight” remains paramount.
The Threat is Changing
Under a five-year defense program adopted at a Workers’ Party Congress this past February, North Korea called for the mass production and deployment of short-range ballistic missiles designed to greatly increase the “density and durability of concentrated attack” against South Korea, which the plan designates as its “most hostile enemy state.”[1] In April, Pyongyang tested cluster munitions and graphite bomb payloads drawn directly from lessons observed in the Middle East, while adding tank systems equipped with Russian-origin drone intercept technology gained from its soldiers’ battlefield exposure in Ukraine.[2] The U.S. director of national intelligence noted in March that the Ukraine war “will continue to have spillover effects in other parts of the globe, as shown with North Korean troops gaining valuable warfighting experience and military technology from Russia.”[3]
The evolving North Korean threat and the accumulation of these new capabilities are not just for deterrence signaling. It is doctrine-integrated warfighting preparation incorporating lessons from Ukraine, Iran, and elsewhere. And while deterring a North Korean nuclear strike remains necessary for the alliance, it is no longer sufficient. China, meanwhile, is on a trajectory toward nuclear near-peer status with the United States.[4] When that threshold is crossed, the logic of extended deterrence in Northeast Asia changes in ways existing alliance frameworks do not account for. A senior Japanese Cabinet aide, speaking in a personal capacity but speaking nonetheless, has publicly called for a nuclear deterrence debate in Japan, a development whose significance lies not in any imminent capability decision but in what it reveals about the stress the current environment is placing on the norms that have stabilized Northeast Asia for decades.[5]
With the DPRK now a multi-domain adversary that uses nuclear threats to create space for aggression below the retaliation threshold in the cyber domain, against critical infrastructure, and through increasingly sophisticated conventional forces, it is clear that alliance architecture needs to evolve and modernize to match the threat environment’s level of strategic uncertainty. The alliance must also recognize that cross-domain deterrence is harder to sustain politically than the frameworks that still dominate the policy conversation.
Washington Without Theory
The architecture-threat gap would be more manageable if Washington were actively working to close it. The deeper problem is that the United States under the second Trump administration no longer has an agreed-on theory of what it wants its alliances to do, nor the political coherence to do it. That internal incoherence is itself a form of strategic vulnerability.
The December 2025 National Security Strategy omits North Korea entirely. Its Western Hemisphere emphasis stood out as much for what it said as for what it left out.[6] The January 2026 National Defense Strategy calls for South Korea’s primary responsibility for deterrence on the Peninsula, but without completing the alliance modernization work required to make that rebalancing coherent.[7]The Trump administration has simultaneously described North Korea as a nuclear power and insisted that denuclearization remains the goal. No North Korea policy review has been completed. And the Iran war has run past all these documents and statements regardless, with a demonstration of what U.S. military power looks like that has illuminated the strategic logic of Pyongyang’s nuclear investments and altered the strategic environment the NSS was attempting to describe.
If and when President Trump sits across from Kim for another effort at nuclear diplomacy, Kim’s delegation will arrive with a clear theory of American objectives. The American delegation will not. That asymmetry is North Korea’s leverage, and it has persisted across six administrations. Trump 2.0 is reprising it with less institutional capacity to manage it than at any previous point.
The pattern is not Korea-specific. On Taiwan, contradictory U.S. signals have generated genuine uncertainty about American intentions in Beijing and Taipei simultaneously. On NATO, burden-sharing demands have been framed as transactional rather than as part of a shared strategic logic, eroding the political foundations that make allied contributions sustainable. The through-line is a Washington conducting a fundamental renegotiation of its alliance relationships without a clear vision of what it wants the renegotiation to produce. Allies have responded rationally—hedging, building redundancy, deepening bilateral and mini-lateral ties—and those adjustments are, in aggregate, beginning to reshape the architecture in ways that may prove difficult to reverse.
Two Definitions of Modernization
The Trump administration’s instinct that allies should bear more of the costs of their own defense is not wrong as a general proposition. The ROK of 2026 has military, economic, and technological capabilities that the ROK of a decade ago, let alone two of three, did not. Expectations that Seoul takes on responsibilities that would not have been realistic to ask even recently are appropriate. The alliance should reflect the partner South Korea has become.
But alliance modernization and burden-sharing conversations are happening across a definitional gap that the public framing obscures. When Washington says alliance modernization, it means something specific: ROK conventional capabilities sized to the peninsula fight, Korean ground forces taking on primary responsibility for that fight, and strategic flexibility for U.S. forces to be employed in regional contingencies, including in Taiwan. When Seoul says alliance modernization, it means something different: a nuclear-powered submarine, a political mechanism for OPCON transition, and an extended deterrence architecture updated to reflect the partner Korea understands itself to be. The two definitions are not incompatible. But they are also not the same. Last year’s leaders’ summits produced communiques that each side could read through its own lens, while papering over concepts of operation that remain undefined.
That gap matters because alliance modernization—not to mention what constitutes burden sharing as opposed to burden shifting—cannot be coherently distinguished without it. A genuine renegotiation toward a new equilibrium in which greater Korean primary responsibility is matched by updated U.S. commitments, genuine consultation, and agreed frameworks for managing the risks being redistributed is one thing. Offloading burdens without transferring the architecture required to bear them or the development of unilateral capabilities or posture that no longer aligns with alliance needs is something else again entirely. Which one is on offer depends on what definition of modernization is operative—and right now, neither side has answered that question.
The nuclear submarine debate is one area where the tension in this ambiguity is pronounced. Korean political expectations have hardened around the platform; many U.S. analysts question whether a nuclear sub makes sense as a primary investment given what Iran and Ukraine have revealed about the dominance of drones, sensors, and missiles in active conflict. A nuclear sub is, among other things, a platform whose strategic logic points toward an eventual nuclear option and whose acquisition cost will come at the expense of the conventional capabilities U.S. planners say they want Korea to develop. The platform debate and the question of U.S. strategic flexibility all sit downstream from unresolved questions about the future of the alliance. Asking the ROK to posture for primary peninsular defense while also accommodating USFK use in Taiwan contingencies, for example, pulls Korean force structure in incompatible directions: the posture optimized for a North Korean fight is not the posture optimized for surviving Chinese strikes on Korean bases used to support Taiwan operations. Seoul cannot do both well, and the alliance has not determined which to optimize for.
Beyond the security domain, U.S. allies are also being asked simultaneously to absorb greater responsibility for regional public goods, such as development, governance capacity, and economic architecture, in a moment when Washington's own contributions to those goods have contracted sharply. Korea is being asked to align economically and on trade as a condition of military assistance and alliance modernization, a conditioning that signals a transactional rather than a strategic logic. That transfer may be defensible. But it is not currently being managed as strategy.
The Illusion of Stable Coexistence
The stable coexistence framing that appears to be emerging as the implicit U.S. posture on North Korea does not resolve these questions.[8] Just the opposite: it defers them to compounding interest. Soviet-American coexistence worked because it was a two-player symmetric game with rough parity and mutual survivability. The Korean Peninsula is a six-player asymmetric game where power disparities are extreme, interests are misaligned, and no single actor has the leverage to enforce the equilibrium coexistence requires. North Korea's doctrine of preemptive nuclear use and South Korea as the principal enemy is structurally incompatible with any coexistence worth calling stable. A bilateral U.S.-DPRK arrangement, moreover, cannot simultaneously satisfy the diverging interests of Seoul, Tokyo, Beijing, and Moscow.
Beneath the surface of “stable coexistence,” then, a proliferation cascade in Northeast Asia is already underway. The greatest security cost North Korea's arsenal may impose on South Korea is not a missile. It is the pressure that arsenal places on a regional order that has depended on non-proliferation as a stabilizing norm.
China’s evolving position adds an additional new dimension to the question, as the standard pressure-Beijing-to-pressure-Pyongyang framework for arresting North Korean proliferation now appears largely exhausted. Beijing is genuinely uncomfortable with the depth of the new Russia-DPRK relationship, with Russia now having disrupted decades of PRC efforts to serve as Pyongyang’s indispensable patron. A North Korea strategically embedded with Russia and less dependent on China may also likely be less controllable, and the real diplomatic opening for a new non-proliferation regime may run through Beijing’s anxiety about losing its buffer state to Russian influence. Exploiting that opening, however, requires a strategic sophistication and institutional capacity that the current policy environment has not demonstrated.
What is to be Done?
The U.S.-ROK alliance can be held together. Will is not the limiting factor. What is required is a Washington that has resolved its own internal debate about what the alliance is for and is prepared to act on the answer with the consistency and institutional seriousness that an ally can trust and build on. That means an agreed theory of what modernization means before terms are renegotiated rather than after. It means updated, extended deterrence frameworks rather than reaffirmed ones. It means completing OPCON transition on a timeline anchored to an honest assessment of ROK capabilities and bridging and enduring U.S. capabilities.
It means institutionalizing the trilateral relationship with Japan rather than leaving it dependent on the personal relationships of incumbent governments. And it means developing an agreed theory of cross-domain deterrence covering cyber, space, and nuclear that the alliance can communicate and sustain politically across administrations in Washington and Seoul.
It also means being honest about what burden-sharing requires in return. If Korea is being asked to absorb primary responsibility for its own defense and to fill regional public-goods gaps Washington is no longer providing, the consultative architecture, technology transfer arrangements, and extended deterrence commitments that underpin those demands need to be made explicit and credible. The alternative is a system that preserves the vocabulary of alliance while hollowing its strategic content—and that discovers, at the worst possible moment, that the form is not a substitute for the substance.
Whether the ROK-U.S. alliance survives Washington’s current ambivalence is perhaps the smaller question. The larger one is whether Washington will develop the strategic coherence needed to work with Seoul to develop a shared and realistic plan for modernization, and the discipline to implement it, and what Seoul will conclude if it does not.
Notes
[1] On the five-year defense program adopted at the Ninth Congress of the Workers’ Party of Korea in February 2026, see 38 North, “North Korea Tests New Theater Launch Platforms as Party Congress Continues Nuclear/Missile Buildup,” April 15, 2026, https://www.38north.org/2026/04/north-korea-tests-new-theater-launch-platforms-as-party-congress-continues-nuclear-missile-buildup/.
[2] North Korea tested short-range ballistic missiles armed with cluster-munition warheads and a graphite bomb during a three-day series of weapons tests on April 7–8, 2026, and conducted a second cluster-munition test on April 19; see Dzirhan Mahadzir, “North Korea Test Launches Short Range Ballistic Missiles with Cluster Munitions,” USNI News, April 24, 2026, https://news.usni.org/2026/04/24/north-korea-test-launches-short-range-ballistic-missiles-with-cluster-munitions/; “North Korea Tests Military Assets Including Ballistic Missile, KCNA Reports,” Reuters, April 8, 2026, https://www.reuters.com/world/asia-pacific/north-korea-tests-military-assets-including-ballistic-missile-kcna-reports-2026-04-08/; and “North Korea Says It Tested Missiles with Cluster Munitions, Blackout Bombs,” NK News, April 9, 2026.
[3] Office of the Director of National Intelligence, 2026 Annual Threat Assessment of the U.S. Intelligence Community (Washington, DC: ODNI, March 18, 2026), https://www.dni.gov/files/ODNI/documents/assessments/ATA-2026-Unclassified-Report.pdf.
[4] See Office of the Secretary of Defense, Military and Security Developments Involving the People’s Republic of China (Washington, DC: U.S. Department of Defense); and ODNI, 2026 Annual Threat Assessment.
[5] The remark was made off the record by a senior national-security aide in the Japanese Prime Minister’s Office in December 2025; see Stimson Center, “When Denuclearization Fades, Japan Holds the Line,” March 13, 2026, https://www.stimson.org/2026/when-denuclearization-fades-japan-holds-the-line/. On Prime Minister Takaichi’s subsequent rejection of NATO-style nuclear sharing, see “Takaichi Draws a Red Line on Nuclear Sharing Amid Japan’s Security Review,” The Diplomat, February 25, 2026, https://thediplomat.com/2026/02/takaichi-draws-a-red-line-on-nuclear-sharing-amid-japans-security-review/.
[6] The White House, National Security Strategy of the United States of America (Washington, DC, December 2025). On the omission of North Korea and the Western Hemisphere emphasis, see “Unpacking a Trump Twist of the National Security Strategy,” Council on Foreign Relations, December 6, 2025, https://www.cfr.org/expert-brief/unpacking-trump-twist-national-security-strategy.
[7] U.S. Department of Defense, National Defense Strategy (Washington, DC, January 23, 2026). On its treatment of the Korean Peninsula and U.S. strategic flexibility, see Center for Strategic and International Studies, “What Does the Trump Administration’s New National Defense Strategy Say About China?,” January 2026, https://www.csis.org/analysis/what-does-trump-administrations-new-national-defense-strategy-say-about-china.
[8] On the “stable coexistence” framing, see, in its softer (risk-reduction and engagement) form, Frank Aum and Ankit Panda, “Pursuing Stable Coexistence: A Reorientation of U.S. Policy Toward North Korea” (Washington, DC: Carnegie Endowment for International Peace, May 6, 2025), https://carnegieendowment.org/research/2025/05/pursuing-stable-coexistence-a-reorientation-of-us-policy-toward-north-korea; and, in a harder (deterrence-forward) form, Victor D. Cha, “North Korea as It Is: The Case for a Cold Peace,” Foreign Affairs, May/June 2026, https://www.foreignaffairs.com/north-korea/north-korea-it-victor-cha.
About the Author
Mr. Michael Schiffer
Senior Fellow, Center for American Progress
Mr. Michael SCHIFFER is a partner at Scalare Advisors and a senior fellow at the Center for American Progress. He has served as deputy assistant secretary of defense for East Asia, on the professional staff of the US Senate Foreign Relations Committee, and as the assistant administrator for Asia at USAID, and as co-manager of the Poipu Bed and Breafast Inn, among other positions.
