Foreign Affairs - NATO’s Permanent Crisis The Alliance Has Survived 80 Years of Disagreement—and It Will Survive Again - Florence Gaub and Jonathan Heist - June 16, 2026

 Foreign  Affairs 

NATO’s Permanent Crisis

The Alliance Has Survived 80 Years of Disagreement—and It Will Survive Again

Florence Gaub and Jonathan Heist

June 16, 2026

At the NATO Cooperative Cyber Defence Centre of Excellence in Kalkar, Germany, April 2026 

Jana Rodenbusch / Reuters

FLORENCE GAUB is Director of the Research Division at the NATO Defense College. 

JONATHAN HEIST is Colonel in the U.S. Army at Supreme Headquarters Allied Powers Europe.

The views expressed here are their own.

Every few months, a new round of obituaries for NATO arrives. Commentators declare the alliance finished, analysts speak of irreparable rifts, and foreign policy veterans reach for the language of unprecedented crisis. This week’s G-7 meetings, taking place under the shadow of new threats from Trump and longer-standing disagreements between Europe and Washington over the war in Ukraine and the U.S.-Israeli war in Iran, have occasioned the latest fit of fatalism.

Their alarm is understandable. In his return to the U.S. presidency, Donald Trump has challenged the transatlantic status quo. He began his second term by criticizing Europe for its paltry defense spending and by questioning Washington’s commitment to Article 5, the alliance’s bedrock collective defense provision. Since then, he has bemoaned member states’ refusal to join the U.S. effort in Iran or grant U.S. forces access to overflight and bases. And his administration has now taken steps to reduce deep-strike military capabilities, including long-range bombers, on the continent.

To many observers, the moment feels like something entirely new. It is not. NATO has been in crisis since the moment it was founded. The alliance has weathered more than a dozen severe episodes of disagreement among members over money, strategy, military operations, nuclear weapons, and the basic question of who owes whom what. Some of these crises produced radical ruptures—France and Greece withdrew from NATO’s military command structure; the United States and its closest European partners worked actively against each other in the UN Security Council; and Washington has threatened drastic troop reductions more than once—but none proved irreparable.

The current crisis, for all its severity, fits a recognizable pattern. Like nearly all of its antecedents, it stems from two sources of tension. The first concerns burden sharing, the perennial American complaint that European allies are spending too little on their own defense and free-riding on American power. The second is out-of-area operations, the equally enduring disagreement about what the alliance should do beyond its treaty boundaries and whether one ally’s security interests are another’s obligation. In every previous disagreement, NATO has found a way through because of members’ shared security interests—and because of the cost of divorce. That those shared interests remain intact today suggests the alliance will again survive.

PRESENT AT THE CREATION

American grievances over European defense spending are not a Trump-era innovation. They are as old as the alliance itself. Europeans have always sought a strong U.S. commitment to their security, and Washington has always sought strong allies to limit its obligations and support its global foreign policy. This tension was built into the alliance’s founding document: Article 5 of the North Atlantic Treaty allows countries the discretion to provide assistance with “such action as it deems necessary, including the use of armed force,” and Article 3 requires allies “by means of continuous and effective self-help and mutual aid, [to] maintain and develop their individual and collective capacity to resist armed attack.”

In 1949, the idea that the treaty would catalyze European self-help—embodied by Secretary of State Dean Acheson’s much-publicized assurance to Senator Bourke Hickenlooper, a Republican from Iowa, that the United States would not have “to send substantial numbers of troops over there as a more or less permanent contribution to the development of these countries’ capacity to resist”—played a decisive role in the Senate’s approval of the treaty. Meanwhile, the lack of concrete American security guarantees prompted British Prime Minister Ernest Bevin to question “whether a pact so weakened is still worth signing.” This dynamic—Americans feeling exploited, Europeans feeling insecure—has never gone away.

The first crisis over spending came quickly, in 1950, after the successful Soviet atomic bomb test the previous year and the communist invasion of South Korea demonstrated the need for a major defense buildup. U.S. President Harry Truman, making the case for a significant deployment of four additional U.S. divisions to Europe, explained to a skeptical American public that the extent of U.S. contributions to such a buildup depended on “the degree to which our friends match our action.” As Congress debated Truman’s proposal, U.S. senators who met with General Dwight Eisenhower, then NATO’s first Supreme Allied Commander, broached their worries that a permanent American command might reduce Europe’s motivation to defend itself. When Congress finally approved the expanded NATO package in 1951, it expected that the deployment would end once European allies completed their economic recovery. That hope was dashed almost immediately.

American grievances over European defense spending are not a Trump-era innovation.

Eisenhower himself believed U.S. troops in Europe were a temporary measure. “If in ten years all American troops stationed in Europe for national defense purposes have not been returned to the United States, this whole project will have failed,” he told a close confidant in 1951. When he left his NATO post to run for president in 1952, European force levels were rising and he was confident the trend would continue. But by 1953, the trendlines had already reversed. The sense of imminent Soviet threat evaporated after Stalin’s death, and European publics began to see NATO as increasingly irrelevant. Defense spending fell, and mutual recrimination followed.

This became the template for nearly every subsequent quarrel. U.S. President John F. Kennedy asked European countries to expand their conventional forces to support defense measures below the nuclear threshold; Europeans argued that the American nuclear umbrella made large investments in conventional weapons redundant. By the mid-1960s, Europe had completed its postwar economic recovery but was devoting a steadily shrinking share of national income to defense, reversing the surge of the early Cold War years. Montana Senator Mike Mansfield led repeated efforts to cut the number of U.S. forces in Europe in half. Harlan Cleveland, President Lyndon Johnson’s ambassador to NATO, spelled out the logic animating Mansfield’s campaigns with unusual frankness: “Unless the Europeans show a lively interest in their own defense, it becomes politically impossible for a government in Washington to represent to its own people that we are partners in a collective security mission.”

In 1977, allies pledged to raise defense spending by three percent a year in real terms. Within years, most were falling short, prompting Georgia Senator Sam Nunn to submit an amendment to a 1984 defense authorization bill that would have mandated a one-third cut in U.S. forces in Europe unless allies complied. The amendment failed, but sufficiently shocked Europeans into making modest increases. NATO’s 2006 Riga summit set a flat spending target of two percent of GDP; by 2014, when Russia annexed Crimea, only a handful of the alliance’s 28 members were meeting it. In 2011, Secretary of Defense Robert Gates delivered a candid farewell address in Brussels that echoed Cleveland four decades earlier: “The blunt reality is that there will be dwindling appetite and patience in the U.S. Congress—and in the American body politic writ large—to expend increasingly precious funds on behalf of nations that are apparently unwilling to devote the necessary resources.” Gates was not breaking with American foreign policy tradition. He was restating it.

What this history reveals is that American complaints about burden sharing are a constant feature of the alliance, but never a fatal one. Each crisis over spending has produced enough European movement to forestall total rupture, even when that movement has been modest, delayed, or reversed in a subsequent period of calm. The alliance proved capable of absorbing enormous amounts of American frustration without breaking because both sides needed each other enough to sustain the relationship through the arguments. That underlying dynamic has not changed.

RIDING SOLO

The other chronic source of NATO crisis—disagreement over military action outside the alliance’s formal treaty area—has been just as disruptive. Article 6 of the North Atlantic Treaty obliges allies to defend against attacks only in the Atlantic Ocean north of the Tropic of Cancer, Europe, North America, the Mediterranean Sea, and Turkey. In practice, members have never agreed on where the boundaries actually lie—or what obligations, if any, flow from them.

The first major rupture came in 1956. Without consulting Washington, France and the United Kingdom coordinated with Israel to seize the Suez Canal, which Egypt had recently nationalized. To the shock of his closest European allies, Eisenhower, judging that the operation would alienate potential partners in the Middle East and undermine Washington’s containment strategy, sided with the Soviet Union at the UN to force the British, French, and Israelis into a humiliating withdrawal. “Such cynicism towards allies destroys true partnership,” said British Prime Minister Anthony Eden. “It leaves only the choice of parting, or a master and vassal relationship in foreign policy.” The damage was severe enough that the North Atlantic Council convened a working group to determine how to re-establish a consensus. Its report, produced by the foreign ministers of Canada, Italy, and Norway, acknowledged that “common interests of the Atlantic Community can be seriously affected by developments outside the Treaty area.” But acknowledging the problem did not resolve it.

Ten years later, France was testing a different version of the same grievance. French President Charles de Gaulle had come to power at a time when France was frustrated over NATO’s lack of support for its counterinsurgency operations in Algeria and still reeling from the Suez abandonment. As the Johnson administration, now mired in Vietnam, pleaded for allied support, material or merely political, de Gaulle withdrew France from NATO’s integrated military command structure. The French initiative angered Americans, many of whom saw the lack of allied support in Vietnam as reflecting, in the words of the historian Lawrence Kaplan, “provocative ingratitude” and as the “culmination of a long series of European offenses against the spirit—and the cost—of the common defense.”

By the end of 1973, the alliance appeared to be over once again.

As a result of de Gaulle’s withdrawal, NATO headquarters was forced to relocate from Paris to Brussels. Supreme Headquarters Allied Powers Europe moved to Mons, Belgium, and the NATO Defense College ended up in Rome. Over 100,000 American and NATO personnel and more than a million tons of equipment were relocated in a single year. The upheaval, along with a financial dispute over troop deployment among the United States, the United Kingdom, and Germany, threatened to completely collapse NATO’s defense posture at a moment of rising Soviet military power. But the alliance endured.

The overlapping crises of the early 1970s were in some respects the most acute in NATO’s history. When Egypt and Syria attacked Israel in October 1973, the United States moved to resupply the Israel Defense Forces and sought allied support. France and the United Kingdom refused to endorse Washington’s cease-fire call. France, Greece, Italy, and Turkey all denied American requests for base and overflight access. Portugal assented, but only after Washington threatened to withdraw its Article 5 commitment to Lisbon. A week after the war began, Arab members of OPEC announced an oil embargo, shattering Western economies and producing a fresh round of transatlantic bitterness. European governments opened formal dialogue to negotiate an end to the embargo. Furious, U.S. President Richard Nixon publicly threatened to withdraw American troops from Europe in response.

Then, in July 1974, Greece and Turkey went to war over Cyprus. Greece withdrew from NATO’s military structure; Turkey suspended U.S. operations at Turkish bases. Later that year, a left-leaning military coup in Portugal in response to the country’s 13-year Colonial War in Africa led the United States to openly consider excluding Portugal from NATO and annexing the Azores, which hosted an American base. Barely a year after what then National Security Adviser Henry Kissinger had deemed America’s “year of Europe,” the alliance appeared to many observers to be functionally over once again.

The post–Cold War period brought a new version of the out-of-area problem. The collapse of Yugoslavia in the 1990s exposed a profound disagreement about allied responsibility: the United States initially refused to intervene, while some European states encouraged Yugoslavia’s dissolution and then found themselves without the military means to manage the resulting wars. NATO’s 1999 air campaign against Serbia, conducted without a UN mandate, was the alliance’s first sustained combat operation. It nearly tore the alliance apart. A combination of political micromanagement, national “caveats” limiting how different countries’ forces could be used, and a growing capabilities gap between the U.S. and European militaries contributed to the United States’ largely unilateral response to the September 11, 2001, attacks.

The swift invocation of Article 5 after the attacks initially galvanized the alliance. But that temporary accord soon cracked, riven by the bitter discord over the U.S. invasion of Iraq. By 2003, Operation Iraqi Freedom had produced what Kissinger called “the gravest crisis in the alliance” in its history. The commentator Charles Krauthammer reflected a popular American opinion when he said the lack of NATO support for the operation marked “the end of NATO’s useful life.”

Most European allies are moving toward or past the two-percent-of-GDP threshold.

Eight years later, when France and the United Kingdom moved to act against Libyan dictator Muammar al-Qaddafi after he brutally suppressed protests in 2011, it was Washington’s turn to hesitate. U.S. Ambassador to the UN Susan Rice told French diplomats, “You are not going to drag us into your shitty war.” President Barack Obama resisted European entreaties to intervene but eventually authorized air strikes, which ousted Qaddafi but left a power vacuum that led to a decadelong civil war, confirming Obama’s initial instinct.

The rift resurfaced in 2019, when French President Emanuel Macron, angry over Turkey’s U.S.-supported invasion of northern Syria, remarked that NATO was experiencing “brain death.” Although framed as a concern over American commitment to Europe, his main concern was that the invasion could have unwanted consequences for Europe and the rest of the Middle East. Macron, along with South Carolina Senator Lindsey Graham, House Foreign Affairs Committee Chair Eliot Engel, and U.S. Defense Secretary Mark Esper, suggested suspending or expelling Turkey from NATO, despite the North Atlantic Treaty having no mechanism to do so.

The U.S.-Israeli war on Iran this year has provoked yet another flare-up of tension. British Prime Minister Keir Starmer spoke for most European leaders when he declared the conflict “not our war” and refused to support efforts to reopen the Strait of Hormuz, much to the anger of Trump, who threatened to draw down troops from the continent in retaliation.

WE FIGHT, WE MAKE UP

When one ally, or group of allies, pursues a security interest that others regard as illegitimate, peripheral, or actively harmful, the resulting argument is never just about the operation; it always resurfaces the deeper questions about NATO’s purpose and whether its members share interests beyond the formal treaty commitment. Those questions have never been fully resolved. But neither have they destroyed the alliance.

Despite the surface tensions of recent years, the lingering shock over Russia’s invasion of Ukraine and the Trump administration’s pressure have finally forced a change in burden sharing. Most European allies are moving toward or past the two-percent-of-GDP threshold, with several planning to exceed three percent. The method that has most damaged allied cohesion—Trump’s openly questioning whether the United States would indeed come to an ally’s defense—has produced the most significant increase in European defense investment in decades. NATO has, once again, found a way to turn crisis into movement.

The out-of-area dimension is more complex. Ukraine is not a NATO member, and the alliance has therefore not invoked Article 5. But the war has functioned as the most significant out-of-area challenge in NATO’s history. Allied states have provided weapons, intelligence, training, and financial support to a nonmember state fighting a nuclear-armed adversary, without any consensus on the extent of that support or a reasonable end state for the conflict. The disagreements—about escalation thresholds, about the timing and conditions for negotiation, about the role of American versus European leadership—are real, but they are not categorically different from the disagreements over Suez, Vietnam, or Iraq. Allies are arguing about interests that diverge at the margins while remaining aligned at the core. Rightly understood, the latest reduction of U.S. forces committed to NATO defense plans is another development in a long-signaled shift by Washington toward other global challenges and theaters rather than an abrupt break from the alliance. Even with fewer fighter jets on European bases, the United States remains committed to NATO’s fundamental goal of preventing further Russian aggression.

The structural reasons for NATO’s endurance now are the same as they have always been. Members of democratic alliances argue because their domestic politics create different preferences and constraints. The deliberate ambiguity of Article 5’s commitment to take “such action as it deems necessary”—not to automatically deploy force—was designed to preserve American flexibility and has repeatedly frustrated European allies who wanted something more categorical. But that ambiguity is also what has allowed the alliance to survive arguments that an alliance with a more rigid treaty structure might not have. The maddening vagueness of NATO’s founding document is part of what makes it durable.

There is also a simpler explanation. NATO endures because its members, when forced to choose, have consistently decided that the alternative is worse. Contrary to the beliefs of those who see in every spat the potential end of the transatlantic relationship, the alliance is not held together by sentiment, shared values, or the memory of two world wars, although all of those play an adhesive role. It is held together by a calculation that the security costs of abandoning it exceed the political costs of sustaining it. That calculation has held through the many crises of the last eight decades; it is holding now. None of this means the current crisis is trivial or that NATO’s future is guaranteed. But the appropriate response to uncertainty is not to mistake a familiar fight for a fatal one.

Topics & Regions: United States Europe Diplomacy Geopolitics International Institutions NATO U.S. Foreign Policy