Mihail Kogalniceanu Air Base in Romania, a key NATO installation on the alliance’s eastern frontier, illustrates the complexity of the United States’ military posture in Europe amid President Donald Trump’s efforts to reshape the 32-nation alliance. Despite troop reductions beginning in 2024, the presence of critical assets such as KC-135 Stratotanker refueling aircraft signals ongoing U.S. reliance on European bases to project power across the continent and into the Middle East.

Since 1999, the base—whose streets bear American names like Alabama and George Washington—has hosted U.S. forces supporting operations in Iraq and Afghanistan. However, the partial withdrawal of roughly half the 2,000 American service members in Romania last year alarmed some NATO members, especially as Russian drone incursions into alliance territory increased. NATO officials and Western defense experts warn that these developments have underlined emerging doubts about U.S. commitment to European security, even as Washington renews investment in critical infrastructure projects across the continent.

Trump’s tenure has been marked by persistent demands that NATO allies boost defense spending and accusations that many countries do not contribute their fair share. While these pressures have resulted in increased European defense budgets—NATO members and Canada combined raised spending by roughly 20% in 2025—some allies have begun to explore alternatives to American military technology and defense contractors. Nations including Canada, Poland, Denmark, Spain, Norway, Turkey, France, and Germany are reportedly seeking ways to reduce dependence on U.S. weapons systems amid concerns about the reliability of American support.

The Trump administration’s approach to NATO reflects broader shifts away from multilateral cooperation toward a transactional, “America First” foreign policy. The administration has publicly threatened troop withdrawals from Europe and linked alliance support to European backing of U.S. foreign policy priorities, particularly in relation to Iran. In mid-2025, the Pentagon initiated a six-month review of U.S. force posture on the continent, emphasizing scrutiny of allies’ financial, ideological, and military commitments. Although a planned announcement to reduce troop levels by approximately 25,000 was delayed due to internal opposition, officials have not ruled out significant cuts.

Despite rhetoric threatening to weaken the alliance, Trump’s administration continues funding substantial upgrades at European bases. In Spain, for instance, the U.S. committed $400 million to improve aircraft facilities at Moron Air Base over the next decade. Similarly, in Romania, the U.S. is investing alongside Romania’s own multi-billion-dollar project to transform Mihail Kogalniceanu Air Base into NATO’s largest air facility in Europe by 2040.

The alliance’s durability remains under stress. European officials point to a “slump in transatlantic trust” that jeopardizes NATO’s core premise of collective defense under Article 5. Russian military activities near NATO borders, including drone incursions in Romania and Poland and sabotage attempts in Germany and Poland, heighten regional security concerns. Russia denies involvement, framing such incidents as provocations intended to sow discord within NATO.

European and U.S. defense experts emphasize the strategic risks of reduced American engagement. Some view European efforts to diversify defense suppliers as a potential backlash to Trump’s pressures, which could weaken transatlantic military interoperability and U.S. defense industry interests. While several European officials express confidence in managing any eventual U.S. drawdown, many acknowledge that the alliance’s deterrence depends on the perception that the United States would defend its partners.

The debate over NATO’s future is shaped by competing political dynamics in Washington. Congressional leaders from both parties, along with defense industry stakeholders, are reportedly positioned to resist large-scale U.S. troop withdrawals from Europe. At the same time, internal Pentagon tensions and skepticism about certain allies’ commitments complicate decision-making.

As NATO marks more than seven decades of strategic partnership, its members face a transition amid evolving geopolitical challenges. The Trump administration’s pressure has prompted increased European defense spending but also introduced uncertainty regarding the alliance’s cohesion and the enduring nature of U.S. security guarantees. The outcome of ongoing U.S. force posture reviews and shifting defense procurement policies will be critical indicators of the post-Trump trajectory of NATO’s collective security framework.