How Europe Can Run an Alliance Designed for U.S. Control

March 28, 2025: During its 76-year history, the North Atlantic Treaty Organization has faced its share of crises, but none have been as grave as what it confronts today. Since returning to office, U.S. President Donald Trump has questioned the two core principles of the alliance’s collective defense commitment: that there is a shared understanding of the threats to NATO members and that security among all those members is indivisible. The United States sided with Russia and against every other NATO member in February when it opposed a United Nations resolution condemning Russia’s invasion of Ukraine. Moreover, Trump has repeatedly called into question NATO’s collective-defense provision by declaring that the United States will not defend allies who “don’t pay”—despite the fact that nearly all NATO members have dramatically increased their defense spending since 2014.

Given Trump’s low regard for the alliance and its collective defense commitment, it would be no surprise if his administration decided to withdraw from NATO. In late 2023, Congress passed a law prohibiting the president from doing this without congressional assent—a bill that, ironically, was cosponsored by then Senator Marco Rubio, who is now Trump’s secretary of state. But if the administration were to decide to flout the law, it is unlikely that the Supreme Court would do anything to stop it. The court has historically deferred matters of foreign affairs to the executive branch and could find that the law itself is unconstitutional.

Even if he doesn’t withdraw from the alliance, Trump has already seriously undermined it. NATO’s Article 5 collective-defense provision—which says that an attack on any alliance member will be considered an attack on all—derives its credibility less from the formal treaty than from a belief among the members that they are all prepared to come to one another’s defense. In practice, this has meant that the United States, with its vast military, would step up to protect any NATO ally that is attacked. Trump’s words and actions since retaking office—including his direct threats against Canada and Greenland, both of which are part of NATO—have eroded these assumptions. As incoming German Chancellor Friedrich Merz stated in February, it is uncertain whether, in a few months, “we will still be talking about NATO in its current form.”

Can NATO survive without the United States, which throughout the alliance’s history has been both its leading member and principal security provider? Theoretically, yes: if the Trump administration withdraws from NATO, the treaty will remain in effect for the other 31 members. Practically, however, the U.S. role in the alliance would be difficult to replace, especially in a short period of time. Given the fundamental changes to U.S. foreign policy under Trump, the most pressing next step for the rest of NATO is to envision a future without the United States and to position the alliance to succeed regardless.

To do so, the other members will need to find more money, buy more time, and secure some measure of continued U.S. cooperation. Leaders in Europe have already freed up more funds, in part by exempting defense expenditures from budgetary restrictions. Now they will have to invest in the kind of critical military capabilities that have long been provided by the United States. They will also need to supply the bulk of the forces necessary to defend themselves—and do so within a matter of years, not decades.

FOLLOW THE LEADER

NATO is unlike any other military alliance. It has its own political and military headquarters, an integrated command structure, common funding, and joint defense planning, training, exercises, and operations. Although these responsibilities are shared among members, the United States plays a pivotal role in each. It is not only the alliance’s largest and most significant military contributor; it has also long insisted that the other members agree to integrate their defense capabilities within this U.S.-led structure, thus ensuring that Washington controls their employment in major military operations.

NATO didn’t start out this way. The United States agreed to sign the North Atlantic Treaty, in April 1949, only at the strong urging of its European partners—who feared Soviet expansionism after World War II. Initially, it was conceived as a collective-security treaty, not a standing alliance or organization. This changed following North Korea’s invasion of South Korea in 1950. That attack served as a warning that the Soviet Union could strike NATO with little or no warning. U.S. policymakers realized that effective deterrence and defense required more than a written commitment but also, most notably, standing forces under a common command and a political body that could mobilize them swiftly in case of a surprise attack.

This is how the North Atlantic Treaty evolved into the North Atlantic Treaty Organization. Member states appointed permanent representatives to the North Atlantic Council, the governing body of the new organization, and agreed to create an integrated military command structure headed by a supreme commander. (The first person appointed to that position, in early 1951, was the U.S. general, and future U.S. president, Dwight D. Eisenhower.) Ever since, NATO has organized collective defense through this integrated process, which assigns to each member the kinds of capabilities they need to procure and deploy. Although members are responsible for paying for and fielding their own armed forces, the joint command plans, trains for, and, if necessary, commands NATO operations.

Integrated defense planning and operations have guided NATO countries for more than seven decades. But this approach has worked only because the United States has played a dominant and unifying role. U.S. military officers have always occupied the key positions of NATO’s command structure, including by assigning the head of U.S. European Command the role of NATO’s supreme commander. The United States’ land, naval, and air forces perform many of the alliance’s critical military functions. The U.S. military also supplies the core components of its integrated air defense network, which protects European skies; its communications networks; and its intelligence, surveillance, and reconnaissance capabilities. Above all, U.S. nuclear weapons, including those that are deployed in Europe and shared with allied forces, constitute NATO’s ultimate deterrent.

In return for providing this ironclad security umbrella, the United States asked that its NATO partners fully integrate their armed forces within this U.S.-led structure. Most were happy to do so, because they saw integration as a form of concrete reassurance that the United States would come to their defense. But some hesitated, most notably Charles de Gaulle’s France, which did not fully trust that Washington would always share Paris’s security interests. Ultimately, France not only developed its own nuclear weapons but, in 1966, left NATO’s command structure, although it remained a member of the alliance.

Although France was singular in its desire for independence, it was hardly the only European country that sought greater autonomy for its armed forces. During the 1970s, as differences over America’s war in Vietnam emerged within NATO, some European members feared that they might get dragged into a war that they did not believe affected their security. In the early 1980s, U.S. President Ronald Reagan’s confrontational stance vis-à-vis the Soviet Union produced growing anxieties that Europe might end up as a smoking, radiated ruin because of differences between Moscow and Washington that they did not share. And some European countries diverged starkly from more contemporary U.S. priorities, including the war in Iraq. After the Cold War, the European Union played a key role in helping European NATO members increase their defense and security autonomy, with EU states pursuing a common foreign and security policy that also featured a growing defense dimension. The 2009 Treaty of Lisbon further enshrined a mutual defense commitment, although it recognized that for members of NATO, the alliance’s collective-security commitment would remain primary.

In theory, the United States accepted Europe’s need to play a greater role in its own security. After all, allowing more European autonomy could result in a more equal sharing of the overall defense burden, a goal of every U.S. administration since the alliance’s founding. But in practice, Washington insisted that Europe do nothing that might undermine the leading U.S. role in NATO or the alliance’s preeminent position in Western security. Greater European contributions to the common defense were fine—indeed, encouraged—but these would need to be in support of NATO and not any independent enterprise. In 1998, U.S. Secretary of State Madeleine Albright warned that the United States would judge any European defense effort from the perspective of what came to be known as the “three Ds”: there could be no diminution of NATO’s role, no duplication of its defense efforts, and no discrimination by the EU against NATO’s non-EU members when it came to defense procurement. As such, any suggestion by the United States’ European partners that they might establish separate headquarters, autonomous armed forces, or other forms of independence was summarily dismissed by Washington as incompatible with NATO’s primacy.

ALL FOR ONE

After insisting for decades on its centrality within NATO, the United States has now indicated it no longer wants to lead the alliance. In his first appearance before NATO, in mid-February, U.S. Secretary of Defense Pete Hegseth made this crystal clear: “Stark strategic realities prevent the United States of America from being primarily focused on the security of Europe,” he said, adding that the transatlantic alliance’s endurance would require “European allies to step into the arena and take ownership of conventional security on the continent.” But other than calling on European countries to spend more on defense—he suggested they dramatically increase their budgets to five percent of GDP—Hegseth didn’t address how Europe might take ownership of an organization that was built and sustained over decades to ensure U.S. dominance and control.

Answering this question now must be the foremost priority for NATO’s other members and the primary purpose of the alliance’s civilian and military leadership. NATO’s new regional defense plans, drawn up since Russia’s full-scale invasion of Ukraine, provide the framework for doing so. These plans set out the specific force requirements that NATO collectively needs in order to defend its northern, eastern, and southern flanks in Europe. If European nations and Canada commit to fulfill most, if not all, of these force requirements over the next few years, it will result in a defense posture that is far less reliant on the United States than it is now.

The Europeanization of NATO will require three things that are currently in short supply: money, time, and U.S. cooperation. The cost of undertaking this fundamental shift will require a significant increase in European defense spending—with members allocating “considerably more than three percent” of their GDPs to defense, according to NATO Secretary-General Mark Rutte. Even with sufficient resources, however, it will take years, if not a decade, to procure the necessary capabilities, train and equip forces, and deploy them into the field. Because of this, Europe will require Washington’s active cooperation in shifting responsibility from the United States to other NATO members. In some areas—notably, nuclear weapons—it isn’t clear anyone would benefit from a wholesale transition.

Fortunately, European leaders seem to understand the challenge they face and are starting to act accordingly. At an EU summit in early March, European leaders agreed to borrow 150 billion euros ($162 billion) for defense production and to exempt defense spending from budgetary rules that limit annual spending for EU members, potentially adding another 650 billion euros ($701 billion) for defense over the next ten years. Significantly, Germany, which has long spent relatively little on defense despite being Europe’s largest economy, has made a major shift in its own spending rules. In March, its parliament agreed to exempt defense spending, intelligence-service financing, and aid to Ukraine from the country’s strict budgetary restraints, a move that could add as much as 400 billion euros ($432 billion) to its defense spending over the next few years. Many other governments are following suit.

These additional defense resources should go to filling out NATO’s force requirements. At a minimum, European member states should commit to providing 75–80 percent of the forces necessary to implement the alliance’s regional defense plans by the early 2030s—and in the longer term to provide nearly all of those forces. This will include developing critical capabilities—including satellite communications and advanced air and missile defenses—to conduct high-intensity and sustained combat operations. European leaders should also double down on recruiting, training, and exercising their military forces.

Yet, even with sufficient money and time, the success of this transition will require Washington’s active support. If the United States were to leave NATO and withdraw from Europe in a rapid and uncoordinated fashion, the integrated structure that has been built up over decades would likely collapse. European countries simply do not have the military and technological resources to immediately replace what has been supplied by the United States—precisely because Washington made it clear to them for decades that building up such capacities was duplicative and wasteful. In some areas, such as nuclear weapons, the United States may even prefer remaining involved with NATO, if the alternative is more European nations building up their own nuclear capabilities.

Europe no longer trusts Washington’s commitment to security on the continent, a collapse of confidence that has already raised far-reaching doubts about the future of NATO. But there is still a way forward that preserves the best of what the alliance has long offered: a strong defense capable of defeating any threat to its security. Europe will now have to finance and provide much of that deterrent. Not counting the United States, NATO’s other 31 members comprise a population of more than 600 million people as well as a collection of economic resources more than ten times those of Russia. These countries, despite having had to rely on the United States for so long, are fully capable of ensuring their future security for themselves. The time to start is now.

IVO H. DAALDER, is Chief Executive Officer of the Chicago Council on Global Affairs and served as U.S. Ambassador to NATO from 2009 to 2013.

Excerpts: Foreign Affairs