National security experts say his false claims on defense issues could undermine the network of military and diplomatic alliances constructed around the globe by U.S. presidents of both parties over the last 70 years.

“Can we drive a better bargain in some cases? Yeah, and [U.S. officials] are always negotiating” for better terms, said Barry Pavel, a former Pentagon official who now is vice president of the Atlantic Council, a Washington think tank that supports NATO and other U.S. alliances.

“But we gain the most out of these alliances because it helps keep threats much farther from our shores than they otherwise would be,” he added.

In Asia, said Zach Cooper, a security expert at the Center for Strategic and International Studies, a nonpartisan Washington think tank, Trump’s suggestion on the campaign trail that he might withdraw U.S. troops or fail to come to the aid of allies in a crisis is generating unease among allies.