The possibility of a U.S. exit from NATO leaves European leaders assessing military capabilities without American might.
The North Atlantic Treaty Organization’s European nations would need to bolster standing militaries by at least 300,000 troops and significantly boost defense spending beyond 3.5 percent of gross domestic product—at least 250 billion euros—while reviving and integrating their industrial base to defend themselves against Russia without the United States.
And they’d need to do that fast, according to a 2025 joint analysis by European think tanks Bruegel and the Kiel Institute for World Economy.
They warn that even with 80,000 American soldiers and airmen stationed on 30 bases on the continent—and the United States’ capacity to rapidly deploy forces—Moscow will test NATO’s resolve “within three to 10 years.”
The once-inconceivable prospect of the United States withdrawing from NATO is now a possibility. President Donald Trump—never a fan of the 32-nation coalition the Pentagon has spearheaded since 1949—has called for a “very serious examining” of the alliance, after its members failed to respond to his appeal to assist in the Iran war or join the U.S. Navy’s Arabian Sea blockade of Iranian shipping.
Trump has vowed Europeans could face a “reckoning” without American leadership and support. Such a departure would require unlikely congressional approval, but the president’s statements are sparking discussion on both sides of the Atlantic about a restructuring of the alliance that would require Europeans to shoulder more of NATO’s burden.
As widely reported, European allies are actively discussing and preparing for a “NATO minus U.S.” scenario. The idea originated in response to Trump’s demand for Europeans to bulk up support for Ukraine in fighting off Russia’s invasion, his threats to seize Greenland from Denmark, and his characterization of member states as “cowards” unlikely to uphold NATO’s commitments.
While Americans have questioned NATO’s post-Cold War resolve since former President Barack Obama’s administration, Europeans in turn have questioned Trump’s reliability in meeting treaty obligations.
In response to Trump’s demand that NATO allies commit 5 percent of GDP to defense, members agreed during the alliance’s 2025 summit to commit 3.5 percent to their militaries—roughly matching the percent of GDP the U.S. spends on its armed forces—and 1.5 percent for infrastructure improvements, such as cybersecurity, crisis response, and adapting roads, rail lines, bridges, and ports to military needs.
By John Haughey
