Throughout his first term, Donald Trump repeatedly threatened to leave NATO, viewing the alliance as allowing other countries to get a free ride on US security guarantees. His former national security adviser, John Bolton, believes Trump would have followed through on this threat if reelected in 2020. This term, despite deepening tensions with Europe, Trump hasn’t said much about leaving the alliance. Secretary of Defense, Pete Hegseth, has avowed that the United States remains committed to NATO. The better question is whether Trump has effectively made the alliance irrelevant. The US is still a NATO member but 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. The principle of mutual defense works if both allies and adversaries believe it’s credible. It’s getting harder to believe with Trump in the picture. His second term has been alarming from a European perspective, with actions including Trump’s abrupt pivot toward Russia, threats toward NATO members, and reports that the president is considering redeploying troops from Germany to Russia-friendly Hungary. European leaders may have thought of Trump’s first term as an aberration but his return made clear that they may dealing with a very different United States going forward whose security commitments can’t be taken for granted. Recent statements from European leaders suggest they are not confident about America’s commitment to the alliance anymore.

Source: https://www.vox.com/world-politics/404139/nato-trump-article-5-europe-russia