NATO and Collective Security: What Each Position Is Protecting

In January 2026, Danish intelligence services formally assessed whether the United States had become a security threat to Denmark. The proximate cause was Donald Trump's renewed threats to acquire Greenland — an autonomous Danish territory — by force if necessary. The assessment was not made public, but its existence was. A NATO ally was evaluating whether NATO's leading power might constitute a danger to its territorial integrity.

The same month, at the Munich Security Conference, German Chancellor Friedrich Merz and French President Emmanuel Macron held discussions about extending France's nuclear deterrent to cover Germany. The possibility of a European nuclear umbrella — replacing or supplementing the American one — was no longer an academic topic. It was being discussed between heads of state, in public, at the world's most prominent security forum.

The month before, in December 2025, the U.S. National Security Strategy had stated explicitly that European allies must assume "significantly greater responsibility" for regional defense. And in June 2025, the Hague NATO Summit produced something unprecedented: all 32 member states, for the first time in the alliance's history, met the 2% of GDP defense spending benchmark — and committed to reaching 5% by 2035. This would require Europe to roughly double its military spending within a decade.

These events did not appear from nowhere. They are the compressed expression of a debate that has been building since the Cold War ended and the original rationale for the alliance — containing Soviet expansion — disappeared. The debate is not only about percentages of GDP. It is about what kind of order keeps the peace, who is responsible for maintaining it, and whether the architecture built in 1949 is still the right answer to the question it was designed to solve — or whether it has become, in some hands, a source of instability rather than a bulwark against it.

What the collective security position is protecting

The argument that NATO is the most successful military alliance in history — that it has kept the peace among great powers in Europe for over seventy-five years, that its collective defense guarantee deters aggression that would otherwise occur, and that the postwar liberal international order it anchors is not a gift from the powerful but a genuine public good whose dissolution would impose catastrophic costs on everyone, including the United States. This position is associated with the mainstream of Western foreign policy and defense institutions — the Atlantic Council, CSIS, IISS — and with writers including Anne Applebaum (Autocracy, Inc., 2024) and Robert Kagan (The Ghost at the Feast, 2023; The Jungle Grows Back, 2018).

The foundational argument is deterrence. NATO's Article 5 collective defense guarantee — an attack on one is an attack on all — creates a credible tripwire that rational adversaries will not cross. Russia's invasion of Ukraine, a non-NATO member, is offered as confirmatory evidence: Moscow carefully avoided striking NATO territory even as it waged a brutal war on its neighbor. The deterrent worked precisely where it existed. Its absence was precisely where the invasion happened.

Sweden and Finland's accession to NATO in 2023 and 2024 — nations with long histories of deliberate neutrality, that had avoided formal military alignment throughout the entire Cold War — is treated by this position as definitive evidence that NATO membership is valued even by those who had lived without it. Both governments, facing a changed security environment after Russia's full-scale invasion of Ukraine, concluded that the guarantee was worth having. Their application was not coerced. It was chosen.

Applebaum extends the argument beyond deterrence to democratic solidarity. In Autocracy, Inc., she documents how authoritarian regimes — Russia, China, North Korea, Iran — share surveillance technology, weapons systems, and governance techniques in a loose but coherent network of mutual support. Against this axis, she argues, democracies require their own institutional infrastructure: NATO, anchored in democratic values and shared security commitments, is irreplaceable not just militarily but politically. To abandon it is to concede not merely a strategic position but an ideological contest.

Kagan makes the interest-based version of the same case: the United States benefits materially from a stable, democratic Europe in ways that dwarf the costs of maintaining the security guarantee. A Eurasian landmass hostile to American interests, with no U.S. forward presence, would require far larger and more expensive military responses than forward deployment costs today. The postwar order is not charity. It is strategic investment.

What this position is protecting: the proposition that credible collective commitments prevent wars that would otherwise occur — and that the accounting for what NATO "costs" must include the wars it has deterred, not only the checks it has written. It is protecting the claim that democracies have obligations to one another that go beyond transactional interest, and that the liberal international order, whatever its imperfections, is better than the realistic alternatives. Most fundamentally, it is protecting the seventy-five-year record as evidence that collective security works — and the warning that dismantling proven institutions for the sake of theoretical alternatives is a gamble whose downside includes catastrophic war.

What the transactional and nationalist critique is protecting

The argument that the United States has for decades been subsidizing the defense of wealthy European nations that are capable of bearing more of the burden themselves, that this misallocation of American military and fiscal resources weakens U.S. capacity to deter China — the primary strategic challenge of this century — and that security guarantees should be conditional on reciprocal contributions rather than unconditional by treaty. This position is associated with the second Trump administration, particularly with Elbridge Colby (Under Secretary of Defense for Policy and author of The Strategy of Denial, 2021), and with a broader right-realist tradition that includes John Mearsheimer, Stephen Walt, and Barry Posen.

The arithmetic is simple and has been cited for decades. The United States constitutes roughly 46% of NATO's aggregate GDP but provides approximately 60% of its combined defense spending. For most of the post-Cold War period, the majority of European allies spent well below the 2% of GDP benchmark they had agreed to. In 2014, only three of the then-28 members met it. Germany — the largest European economy — reached 2% only in 2024, after three decades of comfortable underinvestment.

Colby's case for "NATO 3.0" — a version of the alliance in which Europe takes primary responsibility for conventional defense of the European continent — is grounded in a specific strategic judgment: China is the pacing threat, the Indo-Pacific is the decisive theater, and U.S. military capacity is finite. Arms flows to Ukraine, U.S. troops permanently stationed in Poland and the Baltics, and the ongoing expectation that American extended deterrence covers the continent are, in Colby's framing, consumable inputs whose opportunity cost is reduced capacity to deter a Chinese move on Taiwan. His June 2025 memo pausing arms to Ukraine was an expression of this calculus in concrete form.

Trump's version of this argument is less strategically coherent but politically potent. His statement in early 2025 — "If they don't pay, I'm not going to defend them" — makes Article 5 explicitly conditional in a way that breaks from seventy years of alliance doctrine. This was, his defenders argued, precisely the point: unconditional guarantees produce free-riding, while conditionality produces the Hague Summit outcome, in which all 32 members met the 2% target and committed to 5% by 2035.

The offshore balancing school — associated primarily with Mearsheimer and Walt's 2016 Foreign Affairs essay "The Case for Offshore Balancing" and with Posen's Restraint: A New Foundation for U.S. Grand Strategy (2014) — represents a more intellectually systematic version of strategic skepticism about forward deployment. Their argument is that the U.S. should maintain the capacity to intervene in Europe when a regional hegemon threatens to dominate the continent, but should not maintain permanent garrisons or treaty-based commitments that substitute American military capacity for European political will. Regional powers, when threatened, tend to balance against the threat on their own. U.S. presence prevents them from doing so.

What this position is protecting: the proposition that American military resources are limited and their allocation involves real choices — that maintaining European defense at the current level of U.S. commitment is not free, and that the price is paid elsewhere. It is protecting the fiscal and strategic capacity of the United States to address the threat it judges primary, against the claim that the transatlantic relationship should insulate European security from American strategic priorities. Most fundamentally, it is protecting the principle of reciprocity: that binding security commitments without proportional burden-sharing are not a testament to allied solidarity but a form of strategic welfare for rich nations capable of doing more.

What the anti-militarist and diplomatic critique is protecting

The argument that NATO is not a defensive alliance in any simple sense — that its post-Cold War expansion eastward constituted a deliberate provocation that Russian leaders warned against for decades, that the military alliance framework itself escalates rather than prevents conflict, and that the resources being directed toward rearmament could be used for diplomacy, negotiated security arrangements, and the social investment that actually addresses the conditions producing instability. This position is associated with Noam Chomsky, with economist Jeffrey Sachs (whose February 2025 speech at the European Parliament, "The Geopolitics of Peace," generated millions of views), with historian Andrew Bacevich, and with a significant portion of the European and American left.

The NATO expansion argument runs as follows: after the Cold War ended, Western leaders — beginning with the Clinton administration's decision to expand NATO to Poland, Hungary, and the Czech Republic in 1999, and accelerating through fourteen additional members over the following decades — moved the alliance's boundaries eastward despite informal assurances given to Soviet and then Russian leaders that this would not happen. George Kennan, the architect of Cold War containment, called the decision to expand NATO to include former Warsaw Pact states "a tragic mistake" in 1997, predicting it would produce a "bad reaction from Russia." Jack Matlock, U.S. Ambassador to the Soviet Union under Reagan and Bush, has made the same argument. Sachs, drawing on his direct involvement in Eastern European transitions since the 1990s, told the European Parliament that "the Ukraine crisis is to a very significant extent the result of deeply misguided U.S. policies" — a claim immediately disputed by the majority of his audience.

Chomsky's framing is broader. In interviews and essays spanning years, he has described NATO as "a U.S.-run intervention force" that has exceeded any defensive mandate through its operations in Kosovo (1999, without UN authorization), Afghanistan (2001), and Libya (2011). He argues that a stronger NATO is not a solution to the Ukraine war but a factor in its escalation, and that the framework of military alliance itself forecloses the diplomatic solutions that might end the killing — specifically, a negotiated neutrality for Ukraine on the model of Austria or Cold War Finland.

The left is not unified on this. A significant portion has broken sharply with the Chomsky/Sachs framing, arguing that treating the war as NATO's fault denies Ukrainian agency — that Ukrainians are capable of deciding who their allies are, and that framing Russian aggression as a predictable response to Western provocation treats tens of thousands of Ukrainian civilian deaths as an acceptable price for great-power comfort. This internal rupture is one of the defining tensions within progressive politics in 2025 and 2026.

The opportunity-cost argument extends to the new NATO spending targets. The commitment to 5% of GDP — an additional $2.7 trillion in annual military spending if achieved across the alliance — is an extraordinary reallocation of public resources. Spain's Prime Minister Pedro Sánchez rejected the target as "disproportionate and unnecessary," citing fiscal and social spending concerns. The left version of this argument goes further: the security threat that justifies this reallocation is itself partly produced by the policies — NATO expansion, U.S. military primacy, the refusal of negotiated settlements — that military advocates have pursued.

What this position is protecting: the proposition that militaries prevent fewer wars than they are credited with, and cause more than they are blamed for — that the deterrence logic, applied by all parties simultaneously, produces arms races rather than security. It is protecting the possibility of negotiated solutions that the military alliance framework structurally forecloses, and the civilian lives lost in wars that might have been avoided if diplomatic off-ramps had been constructed and maintained. Most fundamentally, it is protecting the claim that the question "what started this war?" must be answered honestly even when the honest answer is complicated — and that protecting Ukrainian sovereignty does not require pretending that Western policy bore no causal relationship to the conditions that produced the invasion.

What the European strategic autonomy position is protecting

The argument that Europe must develop the institutional, industrial, and military capacity to act independently in its own security — not necessarily outside NATO, but without the permanent dependency on U.S. will, capability, and electoral continuity that has characterized European defense since 1949. This position is associated most prominently with Emmanuel Macron, who has advanced the concept of "European strategic sovereignty" since his 2017 Sorbonne speech, and with Friedrich Merz, whose constitutional reform of Germany's debt brake in February 2025 represented the most significant break from Germany's postwar pacifist fiscal culture in the country's history.

Macron's "I told you so" moment arrived without celebration. He had warned for years — in the face of European skepticism, American irritation, and repeated accusations of anti-Americanism — that treating the transatlantic relationship as a permanent, unconditional guarantee was a category error. "The death of NATO," he said in 2019, was the alliance's "brain death." The Vance speech in Munich in 2025, the Greenland threats in January 2026, and the U.S. National Security Strategy that made European defense explicitly conditional all validated his analysis. The question Macron had been asking — what happens when the United States, for whatever reason, decides not to defend Europe? — was no longer hypothetical.

The institutional response has been substantial. Germany's constitutional amendment exempted defense spending above 1% of GDP from the debt brake, accompanied by a €500 billion infrastructure fund. The EU's ReArm Europe plan committed €800 billion. The €150 billion SAFE (Security Action for Europe) loan instrument was designed specifically to incentivize procurement of European-made systems rather than American ones — addressing the paradox that European rearmament, in its initial phase, dramatically increased dependence on U.S. hardware. American Foreign Military Sales to European allies rose from roughly $11 billion annually in 2017–2021 to $68 billion in 2024. Buying F-35s and PATRIOT batteries now means longer-term U.S. lock-in, which is exactly what "strategic autonomy" is supposed to solve.

The Merz-Macron nuclear discussions at Munich 2026 — publicly acknowledged, if not detailed — represent the furthest extension of this logic. Germany's postwar nuclear taboo was not merely a legal arrangement; it was a cultural settlement that shaped German identity for seventy years. That Merz could raise the possibility of a European nuclear deterrent in public, at Munich, in 2026, measures the distance the debate has traveled in a single year.

Eastern European skepticism remains the position's deepest structural tension. Poland, the Baltic states, and others remain committed to the U.S. security guarantee as the only one they trust. They fear that "strategic autonomy" is French and German shorthand for an EU security architecture that marginalizes them — that they would trade U.S. extended deterrence, which they credit for their current security, for a Franco-German arrangement that might not extend to Tallinn or Warsaw with the same credibility. Poland, spending 4.5% of GDP on defense, is not waiting for European institutions to protect it.

What this position is protecting: the proposition that sovereignty — including security — should not be permanently outsourced, even to an ally. It is protecting European agency: the capacity to make decisions about European security without requiring American approval, or being held hostage to American electoral outcomes. Most fundamentally, it is protecting the long-term viability of European security by insisting that the dependency relationship that has characterized the postwar period is not a stable equilibrium but a structural vulnerability — and that building genuine capacity is not a betrayal of the transatlantic relationship but the only way to put it on durable foundations.