As the White House moves to de-escalate the war in Iran, the United States is confronting not only economic fallout—higher fuel prices and financial disruptions—but growing geopolitical costs that are reshaping NATO. Recent clashes between Washington and its allies over the Middle East conflict have accelerated a conversation in Europe and Canada about whether they can, or should, prepare for a future in which the U.S. no longer provides NATO’s central leadership.
Allies were blindsided when Washington launched strikes without full consultation and then urged the alliance to help reopen the Strait of Hormuz. That sequence, together with repeated public talk by the president about seizing Greenland or pulling America out of the alliance, has deepened mistrust. European capitals are increasingly asking a once-unthinkable question: would the United States come to NATO members’ aid if required?
That anxiety is already changing defense planning, procurement choices and alliance strategy. Four broad developments underscore how uncertain NATO’s near-term future has become.
1) A symbolic U.S. troop drawdown in Germany
The Pentagon recently announced plans to withdraw roughly 5,000 U.S. service members from Germany—about 14% of the longstanding U.S. presence there. While officials describe the move as a review of force posture tied to changing conditions, even a limited pullback carries heavy symbolism. U.S. forces stationed in Germany since the early Cold War have been a visible guarantee of Washington’s commitment to European security.
The decision has also complicated European defense plans. Berlin had been preparing to host U.S.-made long-range missiles as part of its deterrence posture; officials now acknowledge gaps and uncertainty about how to replace certain U.S. capabilities if they are no longer available. Several NATO members have also rebuffed U.S. requests for access to bases during the Iran war, and key partners such as the U.K. have publicly distanced themselves from U.S. policy, saying they will not become embroiled in that conflict.
2) A real loss of trust
Allies’ mistrust tracks closely with Washington’s recent rhetoric and policy moves. Political leaders and public opinion in countries like Germany and Canada have cooled toward the U.S., and diplomatic behavior has followed. Canada’s prime minister has taken a high-profile role in European discussions about rebuilding international order and deepening ties with “reliable partners,” language that reflects frustration with the unpredictability of U.S. policy.
This erosion of confidence is not merely rhetorical: NATO planners have reportedly begun contingency planning that assumes the possibility of diminished U.S. support. That shift has prompted discussions about whether the alliance needs to rethink command relationships, basing patterns and political assurances.
3) Europe and Canada lack some high-end capabilities
Even as European defense budgets have surged since Russia’s full-scale invasion of Ukraine, and many NATO members now meet or exceed the alliance’s 2% of GDP defense spending guideline, there remain key capability shortfalls. Long-range precision strike, strategic air and sealift, advanced ISR (intelligence, surveillance, reconnaissance) and certain logistics and sustainment functions are still dominated by U.S. assets.
Experts warn it could take five to ten years—or longer—for European defense industries and militaries to field credible substitutes at scale. That creates a “vulnerability gap” in the near to medium term that a hostile actor could try to exploit. The accelerated push for more spending and procurement in Europe is a necessary response, but it is a slow, costly process that will require political will and industrial coordination across many states.
4) No single obvious replacement for U.S. leadership
Washington historically provided not just military capabilities but political cohesion across NATO. In the absence of a reliable U.S. lead, Germany, France and the United Kingdom are positioning themselves to assume larger roles. Berlin has unveiled an expansive new defense doctrine identifying Russia as the primary threat and outlining plans to substantially expand its forces over the coming decade. France and the U.K. are also preparing to contribute more to collective operations, with deployments and capabilities aimed at crisis response in maritime theaters.
Still, analysts argue that leadership is likely to be collective: a European pillar of NATO led by several major states rather than a single successor to the United States. That shift will require better coordination among European capitals and likely closer military integration, as well as sustained increases in defense investment.
Implications and the road ahead
NATO member states are already translating higher defense budgets into procurement and capability development, and alliance targets have been raised to encourage a substantial build-up by 2035. But building credible, independent capacity takes time. The transition would also create political and operational challenges: closer European autonomy could be beneficial for transatlantic burden sharing, but a Europe that arms because it cannot rely on the U.S. is not an ideal outcome for Washington or for allied cohesion.
Most experts do not expect an abrupt U.S. exit from NATO—legal and political constraints make a quick, unilateral withdrawal unlikely—but they see a durable shift in how burdens are shared and who exercises strategic initiative within the alliance. For now, NATO is likely to remain intact, but its center of gravity appears to be moving: a future shaped increasingly by European initiative and capabilities, alongside a still-important but less dominant U.S. role.
That reorientation will require managing a risky transition period, closing capability gaps, and rebuilding mutual trust if the alliance is to remain an effective guarantor of collective defense in a more turbulent international environment.