Russia, of course, remains the biggest problem for most NATO countries. Not only is Ukraine in need of more Western ammunition to sustain an existential fight against invading Russian forces, but Moscow has also significantly escalated its threat to NATO. On Tuesday it designated Prime Minister Kaja Kallas of Estonia, a frontline NATO state, a “wanted” person, in a breach of diplomatic norms.

For European allies, however, a greater source of uncertainty is the future of the U.S. security commitment, a fear heightened by Trump’s comments.

Amid the unease, U.S. Secretary of Defense Lloyd Austin announced he wouldn’t attend the NATO meeting in person after being hospitalized for a medical emergency earlier this week.

Trump’s electoral rhetoric prompted the U.S. ambassador to NATO, Julianne Smith, to momentarily shift the focus from Ukraine to U.S. politics when she briefed the media on Tuesday.

“Encouraging the Kremlin to attack any NATO ally or alliance territory really puts our soldiers — U.S. soldiers — and our allies’ soldiers in greater danger,” Smith said, referring to Trump’s statements as “dangerous” and “irresponsible.”

Alliances, she added, “are America’s strength. They are not a charity project.”