...BUCHAREST, ROMANIA - JUNE 11, 2025: In the year 2025, the transatlantic alliance has been under strain. US President Donald Trump and his administration have been pushing hard for European NATO allies to dramatically boost their defense spending — demanding 5% of gross domestic product (GDP) instead of the long-standing 2% target. US Ambassador to NATO Matthew Whitaker has framed this ultimatum as non-negotiable. He has underscored a broader US push for burden-sharing — a stance echoed by senior officials like Vice President JD Vance and Secretary of State Marco Rubio, who insist Europe must assume greater responsibility for its own security. With the war in Ukraine and rising tensions with Russia in the backdrop, this stance is rattling Europe, raising doubts about America’s commitment, and sparking fears of a shrinking US military presence on the continent. Amid diverging strategic priorities, questions about the reliability of US commitments is pushing the historic alliance towards a critical juncture, according to leading security analysts. “I think there’s a lot of unease in the transatlantic alliance,” says Ian Brzezinski, a senior fellow at the Atlantic Council’s Scowcroft Center for Strategy and Security in the US. “There is a very tangible increase in European concern over the reliability of America’s commitment to transatlantic security,” he told Anadolu, pointing to “a bit of a crisis in confidence that President Trump has to address.” On the European perspective, Francois Heisbourg acknowledged Europe’s preference for continued US engagement but noted: “It takes two to tango.” “We know what the Trump administration thinks of us and how it views us,” said Heisbourg, special advisor at the Foundation for Strategic Research (FRS) in France. “Obviously, this is not conducive to great relations.” - US military footprint in Europe Against this backdrop, both experts anticipate adjustments to the US military presence in Europe. “The United States has made it quite clear that it will proceed with force reductions in Europe,” Heisbourg said, adding that he expects a “fully-fledged domestic review” by the US after the NATO summit in The Hague in June. Brzezinski echoes this assessment. “Hopefully he (Trump) will use his participation in the NATO summit ... to reassure the Europeans that America is committed to European security,” he said. This anticipated drawdown is part of a broader global force posture review by the US administration, which Brzezinski suggests “will probably lead to some sort of reduction in US force posture in Europe. How much is hard to say, it’s hard to predict.” This evokes earlier warnings from officials like US Defense Secretary Pete Hegseth, who cautioned that Europeans “can’t make an assumption that America’s presence will last forever.” - Russia-Ukraine war One of the key factors that will determine the future of the alliance will be the ongoing war between Russia and Ukraine. “That will really determine the future of the transatlantic relationship,” Brzezinski says, referring to the conflict, now in its fourth year. He argues that if NATO, despite its “massive overmatching power compared to Russia,” cannot enable a Ukrainian victory, “that will significantly undermine the credibility of the alliance.” If Russia were to win in Ukraine “there will be increased pressure on other Black Sea countries … This will drive the European effort to increase its defense spending,” said Heisbourg, also highlighting the war as a factor that would determine the future of the transatlantic relations. Europe and the US have taken different approaches on the war, with Europe announcing sanctions against Moscow as Washington engages in talks with Russia. Heisbourg suggests that despite this “it is possible, but not likely, that the US will maybe understand that it needs to bring serious pressure to bear vis-a-vis Russia.” For his part, Brezinski welcomes economic sanctions on Russia, but argues they do not go far enough. “Europe is not exercising its military might as decisively and as forcibly as it needs to,” he said. - Europe’s response: ‘Readiness 2030’ and strategic autonomy Faced with US pressure and the Russian threat, European nations have initiated significant defense investment plans, notably the Readiness 2030 initiative. Proposed by European Commission President Ursula von der Leyen, this plan aims to mobilize up to €800 billion ($910 billion) to bolster Europe’s defense capabilities. “It’s time for Europe to step up. It needs to demonstrate strategic power, bring strategic parity to this relationship,” Brzezinski emphasized, in what he says is a pivotal moment for the continent. He criticized some Western European nations’ tendency to be “inward looking” and their reluctance “to recognize the reality, the threat posed by (Vladimir) Putin.” “Now is Europe’s hour. Now is Europe’s moment to stand up and exercise the power it has,” Brzezinski continued, suggesting decisive European action might even garner more robust US support. “Because he (Trump) is not going to do anything more for Ukraine than the Europeans are.”