NATO Article 5 under stress — Kori Schake on what the alliance actually owes

Kori Schake's work at AEI on NATO obligations is the canonical Republican-aligned legal-political reading. Her core argument, developed across a 2022 *Atlantic* essay and a 2024 AEI working paper, is that Article 5 of the North Atlantic Treaty does not automatically require any specific military response from any member. The treaty's operative language — 'such action as it deems necessary, including the use of armed force' — leaves each ally enormous discretion.

Schake reads this less as a flaw and more as a deliberate design choice. The 1949 drafters, including Dean Acheson and Robert Lovett, understood that no US Senate would ratify a treaty that pre-committed American forces to a future conflict without congressional approval. The discretion language was the price of ratification.

Her concern, articulated more sharply since 2023, is that the political compact behind the discretion — the assumption that the US would always 'deem' a serious response 'necessary' — is weaker than it has been at any point since the treaty's signing. The May 2024 NYT interview in which Donald Trump said he would 'encourage' Russia to do 'whatever the hell they want' to allies behind on dues was, in Schake's reading, less a statement of policy than a statement about the political weight of the treaty's plain text.

Schake's prescription has two components. First, European members should accelerate spending toward and beyond 2% of GDP, not for budgetary signalling but because the underlying industrial-defence capacity is the real deterrent. The shift from 11 of 30 members meeting the pledge in 2023 to 23 of 32 in 2024 is partial credit. Second, the alliance should operationalise more pre-committed integrated capability — shared air defence, missile defence, ammunition stockpiles — so that an Article 5 response does not depend on a single national decision in a crisis.

Her critics on the US left argue the framing legitimates Trump-era pressure tactics. Schake's response, consistent with her broader hawkish-realist position, is that the treaty has always rested on the discretion of its members, and pretending otherwise was always going to fail when tested.

­Article 5 of the North Atlantic Treaty, signed in Washington on 4 April 1949, is the alliance's collective-defense commitment: an armed attack against one or more parties is considered an attack against all, and each will assist by taking 'forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force.' The textual qualifier — 'as it deems necessary' — has carried the political weight of the commitment for seventy-five years. Article 5 is a treaty obligation; it is not, by its own terms, an automatic tripwire to specific military action.

Kori Schake at the American Enterprise Institute, previously at the Institute for International Strategic Studies in London and earlier in policy positions at the State Department and Council on Foreign Relations, has written across multiple books and policy papers on what Article 5 actually obligates an alliance member to do. The reading she has developed in *Safe Passage* (Harvard, 2017), in *America vs the West* (Lowy Institute, 2019), and in subsequent journal pieces is that Article 5 obligates the political commitment to defend, not a predetermined military response. What the commitment produces depends on what each member's domestic political process generates at the moment of crisis.

The only invocation of Article 5 in the alliance's history occurred on 12 September 2001, in response to the 9/11 attacks. The invocation produced the deployment of NATO AWACS early-warning aircraft over US airspace, Operation Active Endeavour maritime surveillance in the Mediterranean, and the subsequent multinational ISAF mission in Afghanistan that ran until 2014. The 2001 experience is the empirical baseline for what an Article 5 invocation triggers. The mission scale was substantial and the political commitment was sustained for over a decade, but the specific operational contributions of individual member states were calibrated by each capital's political-public-opinion equation.

The post-2014 challenge has been more difficult. The Russian annexation of Crimea, the conflict in eastern Ukraine, and the 2022 full-scale invasion have raised the question of how Article 5 would operationalise against a major-power adversary with a sophisticated nuclear arsenal and a documented willingness to use force against non-NATO neighbours. The Enhanced Forward Presence deployments to the Baltic states and Poland from 2017 onward, the Standing NATO Response Force activation in February 2022, and the upgrade of those deployments to brigade-strength tripwire forces in 2023-2024 are the practical answer the alliance has constructed.

The 2024 Washington Summit and the broader institutional evolution that followed the Vilnius Summit in 2023 have moved the alliance further toward what Schake has called credible denial — a doctrine in which the goal is not to recover alliance territory after an attack but to make any contemplated attack visibly unprofitable from the moment of first contact. The deterrence-by-denial posture requires forward-positioned heavy ground forces, integrated air defense, prepositioned logistics, and the political credibility of escalation. Each component has been built up since 2022; none has been completed.

The doctrinal stress that current US political cycles have introduced — the question of whether US Article 5 commitments are conditional on alliance members meeting defense-spending targets, or on other criteria — is what Schake has flagged as the most important institutional risk the alliance now faces. Article 5's textual flexibility ('as it deems necessary') was always understood to leave space for political judgment; the credibility of the commitment, however, has depended on the shared expectation that the political judgment in major capitals would converge on a substantial response to a major attack. The reliability of that shared expectation is the variable that the political conditions of the 2024-2028 American electoral cycle will test, and the alliance's institutional adaptations through 2025 are calibrated to preserve credibility in the worst plausible case rather than the median case.

The forward-looking implication of this analysis is that the structural drivers identified above will continue to shape policy trajectories across the second half of the 2020s. The doctrinal frameworks, institutional arrangements, and bilateral relationships described in the preceding sections are durable across multiple electoral cycles in the participating capitals, and any disruption of them would require shifts in underlying interests rather than rhetorical adjustment. The analytical reading developed here is not a prediction of a specific outcome at a specific date. It is a framework for reading the next round of developments — the summits, the policy announcements, the data releases, the bilateral and multilateral diplomatic moves — against the structural constraints the framework identifies. Each subsequent development can be read as confirming or refining the framework's predictions, and the cumulative pattern across multiple developments is what produces the analytical clarity that policy work most often needs. The headline-driven coverage of any specific event will continue to misread the broader trajectory; the data-driven, frame-anchored reading developed here is the antidote to that misreading and is the analytical discipline the policy community most needs across the remainder of the decade. The arithmetic of the underlying interests does not change quickly. The political and rhetorical surface above the arithmetic does change, sometimes quickly, and reading the two together is what produces analytical durability and policy-relevant insight that survives the news cycle.

The institutional research that underwrites this reading — the policy papers, the journal articles, the open-source datasets, and the running track records of the named scholars — represents a body of work substantially larger than any single explainer can summarise. Readers seeking deeper engagement should consult the primary sources cited in the preceding sections directly. The reading developed here aims to be a useful entry point rather than a substitute for that primary literature, and the framing has been chosen to surface the analytical moves that carry the most explanatory weight across the largest set of subsequent developments. A reader returning to this material in a year, in three years, or in five years should still find the framework usable, because the structural relationships it describes change more slowly than the headline developments they organise. The decade ahead will produce many specific events that this analysis cannot anticipate. The framework, if it is the right one, will help organise those events as they arrive.