The lackluster military spending of European countries has been a source of constant complaint for U.S. officials in recent years. Yet most of Washington’s demands for action have lacked credibility, since no U.S. administration has ever penalized a European state for slacking on defense. Instead, U.S. officials have typically sought to reassure allies, in Europe and elsewhere, that the United States would do whatever was necessary to protect them.

The United States’ allies fear that U.S. President Donald Trump may take a different course. Trump spared no criticism during his campaign for Washington’s partners in East Asia, Europe, and the Middle East, suggesting that some of the United States’ security commitments were obsolete and that foreign countries had been reaping the benefits of U.S. protection without providing much in return. Foreign observers variously worried that Trump might send allied states a bill for the upkeep of U.S. forces, withdraw troops to the United States, or refuse to defend their countries from foreign aggression.

Since then, foreign officials have been watching Trump’s appointments, attempting to discern what the new president might demand of U.S. allies. Both Rex Tillerson, Trump’s pick for secretary of state, and Secretary of Defense James Mattis sounded reassuring during their confirmation hearings. The former called NATO’s Article 5 guarantee “inviolable,” and the latter stated that “NATO is vital to our interests.”

NATO leaders watch a fly-past at a summit near Newport, Wales, September 2014. ANDREW WINNING / REUTERS

Still, U.S. allies have reason for concern. Europeans can point to small upticks in military spending this year, but that increase looks significant only when compared with years of substantial reductions, and no major enhancements to the combat capabilities of Europe’s militaries seem to be in the offing. As for South Korea, two weeks after the election, Chang Myoung-jin, the head of the country’s Defense Acquisition Program Administration, said that his government would “inevitably have to” embrace U.S. demands for more military outlays. But Chang’s colleagues in Seoul sharply disagreed, and the political crisis enveloping South Korea will make policy changes difficult. In Japan, too, the political barriers to a more active military role are high: Prime Minister Shinzo Abe’s effort to strengthen the country’s forces continues to face significant public opposition.

Trump said little publicly about his plans for U.S. allies in the weeks before his inauguration. Yet the comments of former President Barack Obama and others who spoke with Trump after the election suggest that Trump wanted to reassure U.S. partners that he is committed to all of them. Obama, for instance, stated that Trump expressed “his commitment to NATO and the transatlantic alliance” soon after meeting with him in November. Moreover, in his inaugural address, the new president promised to “reinforce old alliances.” Taken together, those statements make it seem unlikely that Trump will withdraw U.S. troops from allied countries.

But surrendering to the status quo would be a mistake. As long as Washington adds forces and military tripwires abroad, friendly states will believe the United States is unlikely to reduce its commitments to them—even if their own military contributions fall short. That means they will revert to habit, nodding yes to presidential demands for burden-sharing while ignoring them at budget-writing time. Indeed, despite the heated concerns of the Baltic states, the modest reactions of most European NATO members to Trump’s comments suggest that they are more determined to assuage foreign demands for greater defense outlays than to develop a serious European combat capability.

Instead of worrying about the minor increases in military spending allied states may make, Trump should adopt a more ambitious agenda. He should call on other nations not just to do more on their own behalf but also to take over responsibility for their own defense. The biggest costs of U.S. security guarantees do not come from basing troops overseas; they come from creating and equipping the military units needed to defend allies in the first place.

The security of U.S. allies is a traditional priority, but that security should be a means rather than an end. Washington should defend allies when doing so makes the United States more secure, not when doing so makes only its allies safer. This difference is critical. Montenegro, the Baltic states, and Ukraine, for instance, are irrelevant to U.S. security. Washington’s focus during the Cold War was to protect the populous industrial states in Europe’s west, ensuring that Moscow could not dominate Eurasia. But such control doesn’t appear to be Russian President Vladimir Putin’s goal, and it is well beyond his country’s means, in any case. Although the status of Ukraine, which was historically dominated by the Russian empire and Soviet Union in turn, warrants humanitarian concern, it does not affect Americans’ well-being.

Japanese Prime Minister Shinzo Abe on board the USS Ronald Reagan near Tokyo, October 2015. REUTERS / KYODO

Even war on the Korean peninsula, which would set off a humanitarian tragedy and economic disruption, would not directly threaten U.S. security. Nor would an American withdrawal from the peninsula trigger such a conflict if Seoul more fully employed its vast advantages over the North. In fact, the U.S. military’s presence in South Korea endangers Americans, since it is why Pyongyang targets the United States with invective and seeks to do so with missiles. Washington’s involvement in a conflict with North Korea would encourage Pyongyang to use whatever weapons it possesses.

Trump should focus on handing back responsibility to allies for their own defense, not just getting them to spend more. That should certainly mean developing conventional capabilities sufficient to deter and win wars. Indeed, U.S. allies’ ability to spend more is the most important argument for transferring that responsibility to them in the first place.

The question of whether more U.S. allies should develop nuclear weapons of their own deserves serious debate. The United States could continue to maintain a nuclear umbrella, or it could decide that the risk of being entangled in nuclear war arising from other states’ conflicts warrants the development of separate allied nuclear deterrents. The arguments against such a policy are obvious, yet Europe already has two nuclear-armed nations. And the threat to stand aside if South Korea responded in kind to the North’s nuclear program might be the most effective means to convince China to put more pressure on Pyongyang to denuclearize.

Thus, if the Baltic states and Poland want NATO garrisons, for instance, other European nations should provide them. The latter have far more at stake in the region, as well as a larger cumulative population, than the United States does. Washington should hand off wartime operational command over South Korean forces to Seoul, which should bear the brunt of meeting any North Korean attack. And in Japan, the United States should begin drawing down its oversize military presence in Okinawa, which has provoked the anger of locals. Such steps would reinforce the broader message that fundamental changes to the United States’ security commitments are needed—beyond higher defense spending on the part of foreign governments. Trump got the attention of allied officials simply by appearing to be serious about his criticisms of the United States’ many security relationships. Now he should make serious proposals for change.