By Eric Vandenbroeck and co-workers

For decades, collective European self-defense was merely an aspiration. Today, the time to realize this goal is finally at hand. Momentum in Europe is building: years of marginal steps to bolster European defenses gave way to meaningful action after Russia invaded Ukraine in 2022, and these efforts have accelerated in the six months since U.S. President Donald Trump came into office. European leaders promised a sharp increase in defense and defense-related spending at the NATO summit in June, raising members’ overall budget commitments from two percent to five percent of GDP. To make good on those crucial new pledges, Europe is introducing new financial mechanisms and breaking down barriers to cooperation in its defense industry.

The danger now is that Europe will lose its momentum—and that the United States, by delaying an expected drawdown of forces from the continent, will let it. Both sides have good reason to see Europe’s defense buildup succeed. The United States would be able to free up forces now stationed in Europe for other missions, or simply make cuts and pocket the savings. A more capable Europe would become the kind of partner that Washington wants and needs, and it would gain the freedom to set its strategy as a global power.

 

The Complications

The strategic rationale for a substantial U.S. withdrawal is strong, but, as always, the devil is in the details. Some U.S. forces in Europe are essential to protect the East Coast of the United States from a Russian sea-based attack from the North Atlantic, particularly through the ocean gaps between Greenland, Iceland, and the United Kingdom. Other U.S. conventional weapons stationed on the continent, such as the Rivet Joint, Global Hawk, and P-8 reconnaissance aircraft, collect crucial intelligence. To remove such capabilities would be unwise.

In some cases, the fact that large U.S. weapons in Europe serve multiple purposes precludes a dramatic drawdown. U.S. warships, for example, are badly needed in the Indo-Pacific, and Europe has strong naval capabilities already. But many American ships will need to stay where they are. U.S. naval forces in Europe offer a suite of weapons used for different tasks, some of which they must continue to perform in Europe for the foreseeable future. Take the Arleigh Burke–class destroyer, the U.S. Navy’s workhorse. One cannot remove a destroyer’s Tomahawk missiles, whose land-attack function Europe can be expected to replace, without removing its Aegis radars, which are a cornerstone of Europe’s missile defense network. U.S. Ohio–class nuclear-powered submarines, a key component of the U.S. nuclear triad, require access to in Europe. Maintaining a presence in Europe—particularly the use of the base in Rota, Spain—is also important for the U.S. Navy’s logistics network and power projection to other regions of the world.

The United States clearly should not withdraw all its forces from Europe. Nor should it remove assets too quickly and in too many areas at once, taking away capabilities that Europe’s militaries cannot satisfactorily replace in the next few years. As Washington plans its withdrawal, it must factor in ambitious but realistic expectations of what Europe’s financial resources, bureaucracies, and defense industrial base can accomplish. Washington must also accept that creating gaps as it draws down will bring some risk—otherwise, the drawdown might never proceed—but it should not recklessly expose Europe to Russian attack.

That said, it would be easy to overstate the risks created by U.S. withdrawals and understate Europe’s capability to satisfactorily fill them in. Responsibly managing a drawdown while keeping many essential capabilities in position is not abandoning Europe. But actors with vested interests on both sides of the Atlantic may depict a U.S. withdrawal as such. European leaders who face obstacles in ramping up defense spending and production could cry foul, for example. Supporters of the U.S. Army will also likely argue that because the army is not needed in Asia, it might as well remain in Europe, but this makes no strategic sense when European armies can do the work themselves. To rebut exaggerated claims and resist the pressure to allow unnecessary redundancies, U.S. policymakers must carefully tailor their rhetoric. The way they talk about and carry out U.S. withdrawals must preserve the trust, norms, and processes that give strength to the United States’ relations with Europe. U.S. policymakers, and above all the president, must continue to make clear statements of U.S. support for NATO, clarifying that Washington aims to reform and update the alliance, not to end it.

To ensure that this necessary rebalancing proceeds, the Trump administration must withdraw substantial numbers of U.S. forces from Europe, starting now, and truly shift the burden of the region’s conventional defense onto the continent. Hesitating would undermine Europe’s progress and risk locking in a suboptimal security structure for years to come. To encourage Europe to follow through on its promises, Washington must lay out a realistic, targeted, and phased plan that cuts U.S. troop levels in Europe roughly in half over the next four years while keeping in place forces vital to U.S. security interests or forces that Europe cannot reasonably replace in that time. If a drawdown is executed well, there is little reason to fear that it would end the transatlantic partnership or leave either side less safe.

U.S. Army equipment in Esbjerg Harbor, Denmark, April 2025, sustainable NATO.

 

 

Making It Work

The drawdown itself should be predictable and focused, proceeding in phases and targeting primarily land power and, to a lesser extent, air power. In the first phase, Washington should withdraw the U.S. forces it surged to Europe in response to Russia’s 2022 invasion of Ukraine. Early in the war, U.S. force levels peaked above 100,000—a huge increase from the approximately 60,000 troops stationed on the continent before 2022. These have since been reduced to around 80,000. (The exact numbers change constantly as forces rotate in and out of Europe.) The initial deployment after Russia’s invasion was prudent, given the uncertainty about Russia’s intentions beyond Ukraine, but three years later, it’s clear the threat of an imminent Russian attack is minimal. The Trump administration should therefore announce plans to begin an immediate withdrawal of these forces, to be completed by the end of 2026. In addition to these ground forces, the squadron of U.S. F-35s that is expected to begin operations this fall should join the first round of removals—Europe already has plenty of fighter aircraft of its own and is expecting substantial deliveries of more over the next few years.

Quickly beginning this phase of modest withdrawals will keep the momentum going for Europe to build up its conventional defenses without leaving gaps that are too big for Europe to realistically fill. If Washington were to stop here, however, it would not be doing enough to truly shift the defense burden to Europe’s shoulders. Together with this first round of cuts, the Trump administration should therefore lay out a broader drawdown of U.S. conventional forces with a deadline of January 2029. This will provide the maximum amount of time for Europe to adjust without the deadline becoming so abstract that momentum dissipates.

This second phase should complete (for now) the restructuring of U.S. forces in Europe, cutting them to roughly half of today’s levels and rebalancing them to include primarily naval forces, a smaller proportion of air power, and a limited number of ground forces. To achieve this force mix, the United States should remove the armored brigade combat team that has been rotating through Eastern Europe since 2017, the European combat aviation brigade and artillery capabilities that have been deployed since 2018, and most short-range air defense units. The main purpose of these forces has been to reassure European allies and deter Russia. They have done an excellent job of reassurance—perhaps too good a job. European armies can take over the deterrent function if properly trained and equipped. As U.S. forces are reduced, staff at U.S. headquarters across Europe can also be downsized. Two of the six Arleigh Burke destroyers that the U.S. Navy has sent to Europe since the start of the war in Ukraine should be redeployed to the Indo-Pacific, where the need is greater. Most U.S. fighter aircraft, such as F-35s and F-16s, currently in Europe for deterrent purposes, can be removed as well, given Europe’s large and growing stock of high-end aircraft.

The Trump administration should also discuss with France, Germany, Poland, and the United Kingdom, Europe’s strongest military powers, the possibility of naming a European official as Supreme Allied Commander Europe—NATO’s top command post. This high-visibility position has traditionally been held by the commander of U.S. forces in Europe, but giving a European general this responsibility would accelerate the transition to European leadership of European defense. A senior U.S. officer could serve as deputy. For a short period, rotating American officers into the top position at regular intervals could also ease the handoff.

A drawdown would leave a meaningful backstop of U.S. forces in Europe, including two army brigades, support aircraft, and most naval forces. U.S. command and control, special forces, space forces, theater ballistic missile defense, and other elements that only the U.S. military can provide would stay in place. To avoid unnecessarily irking allies, the United States should also continue to contribute a small, low-cost deployment to NATO’s Enhanced Forward Presence, a force that helps deter a Russian attack on NATO’s eastern flank. Remaining forces would preserve vital U.S. interests: protecting the U.S. East Coast, maintaining nuclear deterrence, and supporting the country’s world-class collection of intelligence.

Still, the withdrawal would free up a large number of U.S. Air Force and Army units, which could be either redeployed to other theaters or deactivated upon their return to the United States, saving the country money. This two-phase plan, moreover, need not be the end of U.S. force restructuring in Europe. Washington could pursue additional drawdowns in the 2030s—or, if changing security conditions make it necessary, send some forces back.

 

Minimum Cost, Maximum Benefit

As with any change, this strategy involves an element of risk. The principal danger is that European militaries might not fill all the gaps created by U.S. withdrawals, thus leaving Europe more vulnerable to a Russian attack than it is today. Europe has made real progress on funding and coordinating a defense buildup, but the work is not finished, and it could still stall—which is why maintaining momentum now is so important.

This risk, however, is ultimately very low. Europe’s current military weaknesses are easily exaggerated, as is Russia’s current conventional threat to NATO. Some European armies do have low readiness levels, but the continent has lots of troops—the members of the European Union alone already have 1.3 million soldiers under arms, roughly the same number as the United States has and slightly more than Russia’s 1.1 million. European combat airpower is highly advanced and could badly weaken Russian forces attempting to invade a Baltic country or Finland. European NATO allies already deploy large units to the Baltics, including German soldiers permanently stationed in Lithuania—something that would have been unthinkable a decade ago. And because European forces would be fighting defensively, should Russia attack, they would not need as many forces as the aggressor to maintain an advantage. Russia, meanwhile, has proven less capable than once feared. For years, frontline countries worried that a lightning-fast Russian operation might topple their governments before allies could come to their aid. In 2022, they all saw that gambit fall apart in Ukraine.

To be sure, even if Europe is generally equipped to handle a possible Russian incursion, some specific U.S. ground systems will be difficult to replace. Long-range artillery and air defenses, for example, are expensive, in high demand, and hard to produce. But Europe’s procurement funds are growing by tens of billions of euros annually, which should make buying and deploying many of these systems possible within the next few years. Europe can also strengthen its arsenal through means other than one-to-one replacements, such as by increasing its drone warfare capabilities.

The United States should do what it can to make this transition as seamless as possible. Just outlining its withdrawal plans will simplify Europe’s defense calculus, as it will make the future more predictable and thus help Europe think practically about its procurement goals. Eventually, many new European weapons will come from European industry, but for the next few years, Europe will still need to buy a great deal from the United States. The State Department should prioritize Europe as it approves sales of the systems the United States is withdrawing, and the Defense Department and the White House should work with U.S. defense firms to overcome their resistance to making the technology transfers necessary to help European industry fill gaps quickly.

In the end, a serious, well-equipped European self-defense will be a more credible deterrent to a Russian attack than a relatively weak Europe perpetually reliant on the United States. The continent, after all, will always have a greater interest in fighting a war over its territory than Washington has in fighting an ocean away. The era in which the United States enjoyed wide latitude to project military power all over the world is long over, and Washington cannot delay making adjustments to avoid a cycle of overspending and relative decline. Downsizing U.S. forces in Europe is a crucial piece of this rebalancing. With a planned and focused drawdown, the United States can allay European fears of U.S. abandonment and retain influence with its allies. The United States needs bold action now to sustain the momentum already underway to realize a credible European self-defense, for its own sake and Europe’s.

 

 

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