Are the United States and Europe still allies? The European public doesn’t think so

You are on your own.

That is essentially the lesson many US allies have taken from the events of the last few weeks, after President Donald Trump and his administration expressed unwillingness to defend European allies “if they don’t pay” and stopped all military aid and intelligence sharing with war-torn Ukraine.

Recent text messages from a group chat of US senior-most national-security officials are at the center of a US national security scandal—because the editor of The Atlantic magazine was inadvertently included in the chat, which featured detailed information about US plans to attack Houthi targets in Yemen. But the vitriol toward Europe was also palpable in that chat, showing European leaders how the Trump administration talks about them behind closed doors:

“I just hate bailing Europe out again,” Vice President J.D. Vance wrote.

“I fully share your loathing of European free-loading. It’s pathetic,” Defense Secretary Pete Hegseth responded.

Trump officials’ belligerent rhetoric and flippant actions against long-time US allies and partners stand in stark contrast with a major US rapprochement with Moscow that has severely undermined Western efforts to isolate Russia on the world stage since it invaded Ukraine in 2022.

Even against this ominous backdrop, NATO Secretary General Mark Rutte has insisted that “the transatlantic partnership remains the bedrock of our alliance” and that NATO can continue to protect Europe through Article 5 of its founding treaty, which states that any attack on one member is an attack on all members. But Trump’s foreign policy has already damaged the alliance by showing that Washington seems to no longer care about keeping its promises.

Because the credibility of US commitments to its allies is being tested, we started the Microfoundations of Collective Defense (Microcode) project, funded by a grant from the European Research Council. This five-year project will track transatlantic views on the credibility of collective defense commitments in NATO. Using sophisticated opinion polling techniques, a research team from Charles University in Czechia and the London School of Economics measures confidence in the United States, Europe, and Russia about whether NATO members—the United States included—would rally together to defend one another. The first results are a cause for concern: US allies and enemies alike increasingly think the United States will flake on its security obligations to its NATO allies. This should worry not only European leaders but US officials, too.

In deterrence, we trust? The most catastrophic scenario for the European defense—one in which the United States withdraws from NATO—seems unlikely to happen, despite Trump’s occasional references to such a prospect. But China and Russia see a growing rupture in transatlantic relations as a weakness and an opportunity to test the limits of Washington’s collective defense commitments. Meanwhile, European capitals may ultimately take Trump’s message seriously, deciding that the United States is not to be trusted as an ally. This could push US allies to exclude the United States from major defense planning, exercises, and acquisitions and turn toward US competitors for reassurance.

Widespread perceptions that the United States might not defend its allies could have disastrous effects. Worst among these may be deterrence failures in which adversaries take advantage of tense transatlantic relationships to take belligerent actions, anticipating little or no consequences when the United States does not step in to protect its allies. During the Cold War, doubts about whether the United States would defend—or even support—its partners underlay Soviet aggression around the world. More generally, scholars have shown that when alliances lack credibility, their members are more likely to be targets of armed attacks.

If deterrence fails due to the lack of US credibility, the prevalence of instability—from foreign interference and coercion to outright war—could soar. The erosion of trust in the United States also weakens US leadership. The military might of the United States has been the cornerstone of US influence globally for over 80 years. But hard power is not the only factor that matters in alliance building. If allies and enemies no longer believe the United States will fulfill its defense commitments, it hardly matters whether President Trump holds an infamously “bigger button.” The result could be an increasing fragmentation of the global security order and a balance of power that shifts away from Washington.

Measuring the US credibility crisis. Should an attack on any NATO member occur, Article 5 of the alliance’s founding treaty stipulates that this should be considered an attack on all members. But many of those members are increasingly worried that the United States would abrogate its obligations and leave its European allies to fend for themselves.

In January, shortly before Trump’s presidential inauguration, the Microcode team ran surveys in five NATO countries—the United States, Canada, the United Kingdom, Germany, and Poland—and in Russia. The same survey was conducted again after the events of recent weeks, and it will be repeated throughout Trump’s second term in office. The project will therefore be able to track how the Trump administration’s rhetoric and policies shift confidence in NATO’s collective defense commitments. (The most recent report is available here.)

The key question in the survey concerned a specific scenario that has long worried Western policymakers and experts: a Russian invasion of one of the Baltic states on NATO’s eastern flank. Analysts worry that this could occur on the pretense of Moscow aiding the country’s Russian-speaking minority, much as Russia claimed it was doing in Ukraine in both 2014 and 2022.

As the chart below shows, even before Trump took office, US allies were uncertain that they could depend on US military support. In the United States, Germany, and Poland, about three-quarters of respondents declared in January that they believed Washington would likely come to aid Latvia if it was attacked by Russia. In Canada and the United Kingdom, that number was even lower, with approximately 65 percent of respondents expressing belief in the US pledge to defend its NATO allies. The truly worrisome picture then emerged in the data from Russia, where only half of the respondents stated they believed the United States would send its armed forces to protect Latvia from a Russian attack.

A follow-up survey in early March 2025—fielded shortly after Washington decided to stop its military and intelligence assistance to Kyiv—showed a dramatic decline of trust in US collective defense commitments. In the United States and Poland—traditionally the key US East European ally—only half of the population now believes that the United States would come to defend a NATO ally if attacked. In Germany and the United Kingdom, this percentage dropped to merely 45 percent and 37 percent, respectively. In Canada, a country currently embroiled in a trade war with the Trump administration, only one-third of the respondents stated their belief in the credibility of the US commitments to European NATO allies.

Although we have yet to receive the next batch of data from Russia, we expect that Russian views will follow a similar trend, with Russian media largely being full of praise for Trump’s administration and Kremlin officials claiming that the new US foreign policy now coincides with Russia’s vision. Seeing the Trump administration’s belligerent rhetoric and actions toward Ukraine and European allies, Russia military planners probably now seriously doubt that Washington would step in to defend its treaty allies in Europe.

Of course, all this is bad news for NATO. Ultimately, the credibility of collective defense commitments is in the eyes of the beholder. And if that beholder is one’s enemy, deterrence can fail. But it is also bad news for Washington.

Get better soon. Our polling results do not reflect the actual odds that the United States will desert its longest-standing security alliance—just the perception of the possibility of this defection. But the trends and patterns shown here should be worrisome.

A lack of faith in the US commitments to NATO could have ruinous consequences beyond Europe. US allies in East Asia and elsewhere must consider the implications of the US abandonment of Ukraine for the credibility of their own security commitments from Washington. During his 2024 presidential campaign, Trump even dodged questions about whether the United States would defend Taiwan against China by demanding that Taiwan pay more for its defense.

The credibility of US security commitments has become a key factor to watch in world politics. The Trump administration can still realize that effective deterrence requires reassurance, and effective reassurance needs trust. If Washington wants to keep its friends close, it cannot let its enemies get closer.

To preserve its alliances, the Trump administration should provide unambiguous diplomatic messaging that reinforces its commitments to allies around the world. Even low-risk reassurance measures, such as rhetorically reaffirming alliance commitments, have proven to be fairly effective at addressing credibility concerns. Beyond the White House, signals of US commitment to its European allies from members of Congress could partially satiate allies’ questions about whether they continue to have advocates in Washington.

On the capability side, the United States should help strengthen European militaries rather than leaving them to their own devices. For example, with insight from the Russia-Ukraine war, Washington can now work to sell NATO members the weapons systems they need for the modern battlefield, from anti-tank missiles to precision-guided rockets. The US military can also improve intelligence sharing to prepare to more efficiently aid NATO allies without sending in troops; strengthen military-to-military consultations, planning, and advising to help allies’ militaries improve; and support and expand NATO programs, including military exercises designed to improve interoperability between allies’ militaries. European leaders, meanwhile, can ease the transition to greater independence from the United States by accelerating defense spending commitments, enhancing joint military procurement, and expanding intra-European cooperation (potentially including Canada) to strengthen the NATO alliance from within.

As US foreign policy drifts away from traditional alliance building, the willingness of the Trump administration to uphold US commitments will be an essential determinant of how the global order transforms in the months and years to come. Unless Washington restores its credibility as an ally, it might find itself alone to face its next security crisis.