Throughout his first term as president, Donald Trump repeatedly threatened to leave NATO, an alliance that in his view allows other countries who don’t spend enough on their own defense to get a free ride on US security guarantees. His former national security adviser John Bolton has written that he believes Trump would have followed through on the threat if he’d been reelected in 2020.

This term, though, despite deepening tensions with Europe, Trump hasn’t said much about leaving the alliance. His secretary of defense, Pete Hegseth, has avowed, “The United States remains committed to the NATO alliance and to the defense partnership with Europe. Full stop.”

At this point, the better question is whether Trump has effectively made the alliance irrelevant. The US is still a NATO member. But Trump has consistently undermined its core principle that members will treat any attack on another member’s territory as an attack on their own, and come to the attacked member’s aid.

This principle of mutual defense only works if both the allies and their adversaries believe that it’s credible — that countries would actually put the lives of their own citizens on the line to defend allies.

In the case of Trump and NATO, the guarantee is getting a lot harder to believe.

“Would Donald Trump choose to go and fight for Estonia?” said Dalibor Rohac, a senior fellow and expert on European politics at the American Enterprise Institute. “I think at some level, it requires a suspension of disbelief to think that he would.”

Trump’s second term has already been far more alarming, from a European perspective than the first, thanks to actions including Trump’s abrupt pivot toward Russia in the Ukraine war, the Oval Office humiliation of Volodymyr Zelenskyy, his new tariffs, JD Vance’s combative speech at the Munich Security Conference, the territorial threats toward NATO members Canada and Denmark, and reports that the president is considering redeploying troops from Germany to Russia-friendly Hungary.

European leaders might have thought of Trump’s first term as an aberration, a bizarre four years followed by a return to normalcy. His return to the White House made clear they may be dealing with a very different United States going forward — one whose security commitments can’t be taken for granted in the long run, even if Trump is replaced by another Joe Biden-style transatlanticist in four years.

Recent statements from European leaders suggest they are not so confident about the credibility of America’s commitment to the alliance. “I want to believe that the US will stand by our side, but we have to be ready for that not to be the case,” French President Emmanuel Macron said in a recent televised speech to the nation.

“Strategic autonomy” from Washington has long been a priority for Macron, and something of a French tradition dating back to the formation of the alliance. It was more surprising to hear Germany’s likely incoming Chancellor Friedrich Merz, hailing from a center-right party with a strong transatlanticist tradition, say that “After Donald Trump’s statements…it is clear that the Americans are largely indifferent to the fate of Europe” and that Europe must work as quickly as possible to “achieve independence from the US.”

Some of this work will involve steps to increase defense spending, military readiness, and aid to Ukraine

© Vox