Participating in a U.S.-led military exercise, near Xanthi, Greece, June 2025. Louisa Gouliamaki / Reuters

The NATO summit held two weeks ago in The Hague deliv­ered on the low expectations the allies had set for it. Amid fears that U.S. President Donald Trump would blow up a normal agenda, NATO leaders significantly pared back the program, taking hard discussions on issues such as support for Ukraine, NA­TO’s relations with Russia, and Russian hybrid attacks in Europe off the table. But the summit did close with a historic agreement by most allies, Spain being a notable exception, to increase members’ defense spending to five percent of GDP over the next ten years, with 3.5 percent earmarked for core military spending and 1.5 percent for hardening civilian in­frastructure and overall resilience. The pledge to spend more on defense, in ad­dition to NATO Secretary General Mark Rutte’s sycophantic praise of Trump at the summit, smoothed the way for Trump to stick largely to the summit’s highly choreographed script, keeping the alliance’s cohesion intact. Trump even appeared to leave The Hague with a new­found appreciation for NATO members, telling reporters: “These people really love their countries. It’s not a rip-off, and we’re here to help them.”

Any sense of relief among the allies, however, may be short-lived. The rela­tively positive headlines coming out of the summit obscure the storm brewing across the Atlantic. The Trump admin­istration is undertaking a sweeping force posture review slated for release in late summer or early fall that could funda­mentally reshape the U.S. military’s global footprint. If that process results in a significant and swift reduction of U.S. forces in Europe, an outcome that administration officials have publicly suggested is possible, the alliance will become more vulnerable to further Rus­sian aggression.

Europe is stepping up in a big way, and defense budgets are rising, but it will take time to ramp up production and deliver the capabilities that the United States currently provides on the continent. The United States may see fit to make some force adjustments in Europe that allow it to bolster its defense posture in Asia to counter rising threats from Chi­na. But Washington must carefully plan any such shift, leaving U.S. forces in place long enough that Europeans can work to fill the coming gaps and retain their cred­ible deterrent against Russia. It is critical that any drawdown be closely coordinat­ed with NATO military authorities and that allies agree in advance to cover lost capabilities. Otherwise, Russian Presi­dent Vladimir Putin will be tempted to take advantage of a weakened alliance.

The political signals surrounding the U.S. Defense Department’s force posture review have only increased European al­lies’ fears that a rapid drawdown is com­ing. In a speech at his first NATO defense ministers meeting in February, Secretary of Defense Pete Hegseth underscored the Trump administration’s view that Eu­rope could no longer be a U.S. priority, saying that given the “strategic realities,” European NATO leaders “should take primary responsibility for defense of the continent.” Those comments contrast­ed sharply with the message Hegseth delivered in Singapore in May, when he underscored the U.S. commitment to the Indo-Pacific and called it the United States’ “priority theater.” Media coverage of the Pentagon’s 2025 Interim National Defense Strategic Guidance—issued this spring as a placeholder for the National Defense Strategy, which is expected to be released late this year—suggests that the department intends to fund a military buildup in the Indo-Pacific by diverting resources from other places, including Europe, and accepting greater risk in those areas. Even Matthew Whitaker, the U.S. ambassador to NATO, said in May that Washington was “not going to have any more patience” when it came to reducing the U.S. presence in Europe.

The Trump administration’s attitude toward Russia is also feeding NATO al­lies’ concerns about the U.S. commitment to Europe. Trump has been reluctant to define Russia as a threat, instead calling Putin a “good guy” and making clear his aim to normalize U.S. relations with Moscow. Senior U.S. officials have also downplayed Putin’s risk to Europe. Steve Witkoff, Trump’s special envoy for the Middle East, who also oversees diplo­macy with Moscow, said in an interview with the conservative broadcaster Tuck­er Carlson in March that it was “prepos­terous” to think that Russia would “march across Europe”—a straw-man argument meant to suggest that Europe­an assessments of the Russian threat are overblown. NATO allies had planned to present a Russia strategy for approval at the June summit but suspended it in fear that they could not get Trump on board.

Even if Moscow does not march across Europe, Russia will pose a threat to NATO. The Russian military, although not without its flaws, is no longer the disorganized force it was just over three years ago, when it launched its full-scale invasion of Ukraine. Since February 2022, Putin has transformed Russia’s economy and military to support pro­longed confrontation. Russian defense spending in 2025 amounts to 7.7 percent of GDP, a 12 percent increase from 2024. Moscow’s defense industrial base is running at full capacity. As Rutte said at Chatham House in June, “The facts are clearly there that Russia is able, within five years, to mount a credible attack against NATO territory.” Multiple Euro­pean intelligence agencies have arrived at similar conclusions. Washington can ill afford to rapidly reduce its presence in Europe just as Russia is gearing up for further aggression.

NATO has been overly dependent on the United States for its military ca­pabilities since the alliance’s founding, in 1949. After the Cold War, when most European militaries substantially cut their defense budgets, this dependence only deepened. The United States also lowered its defense expenditures and reduced its forces in Europe, from about 300,000 during the Cold War to about 100,000 troops today (including 20,000 additional forces Washington deployed in 2022 in the wake of Russia’s invasion of Ukraine). But despite this decrease in manpower, U.S. capabilities have remained key to NATO’s posture, plans, command and control, and force models. Today, the U.S. Army supple­ments NATO forces along the alliance’s frontier with Russia in the Baltics and Romania, and it maintains permanent bases in Germany and Poland. The U.S. military also stores equipment, its Army Prepositioned Stocks, in Bel­gium, Germany, Italy, the Netherlands, and Poland to outfit army reinforce­ments that arrive by air. The U.S. Navy has six Aegis-class destroyers deployed at a U.S. base in Rota, Spain, to support NATO’s missile defense and take on oth­er maritime tasks in European waters, such as maritime patrols in the Baltic Sea. The U.S. Air Force has combat and support squadrons stationed at allied bases across NATO territory, from the Incirlik Air Base in Turkey to those in Germany, Italy, Spain, the United King­dom, and the Azores.

Should U.S. military capabilities be removed from NATO defense plans, Eu­rope would be unable to quickly fill the resulting gaps, creating vulnerabilities that Putin would be tempted to exploit. U.S. intelligence, surveillance, and recon­naissance platforms, for example, are es­sential for NATO’s awareness of Russian activity. Their withdrawal would leave the alliance especially vulnerable to Rus­sian hybrid attacks, such as undersea ca­ble sabotage, jamming, or cyberattacks. Fewer such resources would also limit early warnings about incoming attacks and hinder NATO’s ability to select, prioritize, and engage Russian targets in the event of conflict. The personnel that process, analyze, and fuse this intel­ligence—many of them American—are too specialized to replace quickly and of­ten in short supply.

Europe also remains highly reliant on U.S. air-to-air refueling tankers, heavy lift aircraft, and other such “strategic en­ablers” to move forces across the conti­nent and supply it with battlefield intelli­gence. Despite European allies’ progress on procuring the military equipment needed to meet their newly mandated responsibilities in NATO planning, they have made less headway in developing these particular capabilities at scale. NATO would therefore struggle to move troops and equipment quickly across Eu­rope in a crisis, just as it did after Rus­sia’s full-scale invasion of Ukraine, when some allies relied on the United States to transfer their troops to eastern Europe to reinforce the eastern flank. With a pared-down U.S. presence, critical shortfalls of air and missile defenses would also be­come even more acute, leaving allied forc­es and countries that are within striking distance of Russian missiles and drones particularly vulnerable.

Other essential capabilities—long-range precision missile systems such as HIMARS, stockpiles of precision-guided munitions, and advanced drones—could also be diminished by a premature U.S. withdrawal. One of NATO’s key deter­rents against Russia is its credible abil­ity to target high-value assets within the country. Losing stocks of long-range missiles would significantly erode this deterrence and increase Europe’s vulner­ability in the event of a Russian attack. And these capability gaps do not exist in isolation. The United States provides Eu­ropean militaries with most of their sus­tainment units, including medical and logistics personnel and a large share of specialists in cyber, space, and electron­ic warfare. Even as European countries ramp up defense spending, the timelines for assuming the functions the United States fills today will stretch into the next decade.

The Kremlin would likely see a rap­id U.S. drawdown in Europe as a golden opportunity. Moscow has long sought to undermine NATO, seeing its demise as a critical step toward reasserting Rus­sia’s position as a global power. Most im­mediately, the Kremlin would seize on any U.S. retreat to amplify Europeans’ anxiety that Washington is abandoning them. With Europe feeling vulnerable, Moscow would ratchet up its coercive tac­tics to intimidate European publics and pressure their governments to be more accommodating to Moscow.

As Russia perceived gaps in NATO’s conventional forces, Moscow would prob­ably become more willing to take risks to advance its aims. Putin would assume that with a smaller U.S. presence in Eu­rope, the West would be forced to favor de-escalation, creating an environment the Kremlin would view as exception­ally permissive and paving the way for increasingly brazen acts. Moreover, Rus­sia has long viewed Europeans as suppli­cants of Washington, unable to function effectively without U.S. direction. If the United States goes forward with a rapid reduction in forces, Moscow might judge that European unity would collapse, fu­eling Putin’s propensity to overestimate Russia’s ability to achieve its goals.

Most immediately, Putin would look to further scale up gray-zone activities in Europe, such as cable cutting and other forms of sabotage. With fewer U.S. intelli­gence, surveillance, and reconnaissance assets in place, such acts would be harder for European countries to detect or attri­bute, allowing Moscow to operate with greater impunity. Beyond hybrid attacks, Russia could be tempted to take limited military action. Because a reduction in U.S. assets in Europe would lead to slow­er NATO response times, Putin might have greater confidence that Moscow could successfully seize territory, for ex­ample in a Baltic state or in Svalbard, a strategic Norwegian archipelago in the Arctic, and then use coercion and nu­clear threats to compel NATO to accept the result. With air and missile defense in short supply and long-range missiles withdrawn, NATO could find it challeng­ing to mount an immediate and coordi­nated defense—undermining NATO’s credibility and dramatically altering the European security order.

Russia is not going away, and Europe’s buildup will take time. If the United States does plan to reduce its troop de­ployment in Europe, simply notifying the alliance that such a change is underway will be woefully insufficient to ensure NATO’s continued ability to protect its members. To avoid a dramatic blow to the alliance’s defenses, allies must pro­cure today what they will need to quickly fill the gaps tomorrow. NATO military authorities must be given time to review and update their battle plans, and indi­vidual countries with the means to do so must commit to replicating specific capabilities that that will be lost as the United States pivots.

Pulling back as Russia is ramping up its military capacity and before Europe is ready to defend itself would embolden the Kremlin and raise the risk of anoth­er war—this time on Trump’s watch. The best way to prevent a future war in Europe is to make sure Moscow never dares to start one. And that will require Washington and its European partners to design a careful and coordinated handoff. The United States must tell its partners exactly where any new gaps will be—long before they appear.

ANDREA KENDALL-TAYLOR is Se­nior Fellow and Director of the Trans­atlantic Security Program at the Cen­ter for a New American Security. From 2015 to 2018, she was Deputy National Intelligence Officer for Russia and Eurasia at the National Intelligence Council.

JIM TOWNSEND is an Adjunct Se­nior Fellow at the Center for a New American Security. From 2009 to 2017, he served as U.S. Deputy Assistant Sec­retary of Defense for European and NATO Policy.

KATE JOHNSTON is an Associate Fel­low at the Center for a New American Security.

Source: FOREIGN AFFAIRS (https:// www.foreignaffairs.com), July 10, 2025.