What’s America need allies for?

• The menu. Historically, the answer has been: a lot—burden-sharing in conflicts, bases on foreign soil, trade leverage, intelligence cooperation, diplomatic cover. Here’s where things seem to be shifting most, though: the global military footprint, intelligence sharing, sanctions coordination, the still-emerging contest with China, other powers’ willingness to make long-term bets on their relationships with Washington, and democracy as an organizing system.
• The global footprint. The U.S. military operates from roughly 750 bases in 80 countries. Ramstein in Germany, Okinawa in Japan, Diego Garcia in the British Indian Ocean Territory—none of these are where they are without host-nation agreements. Those agreements rest on relationships. When allies start hedging, basing rights become negotiations rather than assumptions. The Greenland threats have already prompted Danish Prime Minister Mette Frederiksen to warn that a U.S. attack on a NATO ally would mean “everything stops”—including NATO itself. Other allies are doing their own math.
• Intelligence. Five Eyes—the U.S., the United Kingdom, Canada, Australia, and New Zealand—pool signals intelligence in ways no single country could replicate. NATO has its own architecture. These systems have proven resilient through various shocks. But they’re not unconditional. In November, the U.K. suspended intelligence sharing with the U.S. about suspected drug-trafficking vessels in the Caribbean—because it didn’t want its information used to select targets for military strikes it considers illegal. Canada and Colombia followed. The system depends on allies believing they won’t be made complicit in operations they can’t defend.
• Effective sanctions. The U.S. can put sanctions on anyone it wants. Making them stick is another matter. When Washington sanctioned Russia after 2014, the measures hurt because Europe joined. When it sanctioned Iran while Europe stayed in the nuclear deal, Iran had other buyers. The Venezuela operation takes a different approach: direct control of the oil through threats to the interim regime. Whether that holds without broader cooperation—over months, not days—is now an open question.
• Soft power. For decades, the U.S. built and defended the rules-based, liberal-international order—the United Nations, the World Trade Organization, the architecture of international law. That gave American action a legitimacy that raw power alone couldn’t buy. This week, China’s foreign ministry has been busy, condemning “hegemonic acts” and positioning Beijing as the defender of sovereignty and international law. Opportunistic, given China’s record. But when Washington captures an antagonistic head of state and threatens a NATO ally in the same week, countries in Latin America, Africa, and Asia hear something familiar—and it isn’t the rule of law.
• The long game. Allies make long-term investments—buying U.S. weapons systems, aligning supply chains, hosting infrastructure—because they expect the relationship to continue. When that expectation wobbles, they hedge. Germany is already discussing defense procurement from European suppliers. Japan has been quietly diversifying. Once allies start planning for a post-American world, those plans can develop their own momentum.
• Democracy as a system. The alliance network isn’t just a military arrangement; it’s a coordination mechanism for democratic states. NATO, the Group of Seven (Canada, France, Germany, Italy, Japan, the U.K., and the U.S., with the EU as a “non-enumerated member”), the Quadrilateral Security Dialogue (Australia, India, Japan, and the U.S.)—these are forums where democracies align against autocratic pressure. If the U.S. treats allies as subjects rather than partners, the system doesn’t just weaken; the organizing principle changes. And the U.S. has a stake in democracy abroad: Democracies tend to be peaceful, trade more openly, and not to generate the kinds of threats that pull America back into intervention. They also collectively represent the fundamental liberal-democratic ideals American society and government are predicated on.

None of this yields a single verdict. Things like military bases or intelligence networks are tangible—you can measure what’s at stake with them. Legitimacy, the long-term bets allies make, the cohesion of democratic states: harder to measure, easier to dismiss—though we have to expect, much harder to rebuild once gone. The Trump administration’s bet seems to be that allies will grumble and fall in line. And maybe they will.

But the United States did try something like this before—as the American president knows. In his January 4 press conference, he invoked the Monroe Doctrine (or intended to, in his reference to “the Donroe Doctrine”). The original doctrine dates to 1823, and the Roosevelt Corollary of 1904 (named for President Theodore Roosevelt) extended it to assert American dominance over the Western Hemisphere—the right to intervene, to police, to exclude outside powers. And it worked, in the sense that the U.S. got what it wanted in the short term. But American interventions in Nicaragua, Haiti, the Dominican Republic, and Cuba—they didn’t exactly produce stability. They produced resentment, recurring crises, and costs that mounted over decades.

President Franklin Roosevelt reversed course in 1933. The Good Neighbor Policy renounced intervention and treated Latin American states as partners rather than subjects. The post–World War II order extended that logic globally—through institutions, rules, and alliances that served American interests precisely because they weren’t just American. The U.S. led by building systems others wanted to join.

Whether America still lives in, or should be trying to cultivate, a world grounded in this postwar order is the question the administration is now testing. But the answer won’t come from anyone’s ideological framework. It will come from Copenhagen and Canberra, from the calculations allies make over the coming months and years, from what actually happens when they have to decide what kind of partner America has become.