WASHINGTON — Montenegro may have a few questions for President Trump.
In an interview that aired Tuesday evening with Fox News host Tucker Carlson, Mr. Trump appeared to suggest that the NATO mutual defense compact is confusing, particularly the question of why an American would have to defend a small country like Montenegro, which is more than 5,000 miles away.
Mr. Trump has long raised questions about the future of the United States’ commitment to NATO, a defense treaty which was established to stave off aggression from what was then the Soviet Union. Montenegro joined the alliance in 2017, a year after Russia plotted a coup to overthrow Montenegro’s government and replace it with one that would be hostile toward NATO.
On Tuesday, Mr. Carlson asked Mr. Trump, “So, let’s say Montenegro — which joined last year — is attacked, why should my son go to Montenegro to defend it from attack? Why is that?”
Mr. Trump immediately acknowledged the concern.
“I understand what you’re saying,” Mr. Trump said. “I’ve asked the same question.”
The answer, which Mr. Trump did not articulate in the interview, can be found in Article 5 of the treaty: If one NATO country is attacked, all NATO countries would be considered under attack as well and would join in defense.
The president continued, “Montenegro is a tiny country with very strong people.”
He added, “They have very aggressive people. They may get aggressive, and congratulations, you’re in World War III, now I understand that — but that’s the way it was set up.”
Neither the White House nor Montenegro’s embassy in Washington immediately responded to requests for comment.
Andrew S. Weiss, a vice president at the Carnegie Endowment for International Peace, said the president’s comments on Montenegro sounded as if they were lifted from Kremlin talking points.
“Who on earth could have planted this riff in his head about tiny Montenegro possibly starting World War III?” Mr. Weiss wrote in a Twitter post on Wednesday.
Mr. Carlson interviewed Mr. Trump in Helsinki, Finland, on Monday, after Mr. Trump met privately with President Vladimir V. Putin of Russia.
Richard Haass, the president of the Council on Foreign Relations, called Mr. Trump’s comments “extraordinary.”
“It is not just that the president throws Montenegro under the bus; he makes the US commitment to NATO conditional and makes clear his discomfort w Article 5 and collective security, the core of the alliance,” Mr. Haass wrote Wednesday on Twitter.
Montenegro has not been a country Mr. Trump typically discusses. During a NATO conference last year, video footage showed Mr. Trump pushing past the Montenegrin prime minister, Dusko Markovic, as he made his way to the front of a photo opportunity of NATO country leaders.
Mr. Trump has been accused of vastly misunderstanding how NATO works, and he has distanced himself from the agreement by saying it was in place before he became president. Mr. Trump’s main contention with NATO has been his belief that the United States pays more for defense than other member countries.
“It was very unfair. They weren’t paying, so we’re not only are we paying for most of it, but they weren’t even paying and we’re protecting them,” Mr. Trump said to Mr. Carlson during an interview taped on Monday and aired Tuesday evening. “Add that to your little equation on Montenegro.”
To be sure, respected national security officials in past administrations have cautioned about giving NATO membership to new, smaller nations in ways that might not actually increase the security of the United States or the alliance as a whole.
Robert M. Gates, who served as defense secretary for former Presidents George W. Bush and Barack Obama, made the case in 2008 for the importance of an unwavering commitment to Article 5 of the alliance — the mutual defense agreement binding all NATO partners.
But, without mentioning any specific nations, he noted the potential danger of new members entering the alliance and bringing in increased risks. At the time, there was a debate over whether Georgia should be part of NATO. Russia and Georgia fought a war in 2008, and Russia has occupied parts of the country since.
“We need to be careful about the commitments we make, but we must be willing to keep the commitments once made,” Mr. Gates said. “In the case of NATO, Article 5 must mean what it says. As the allied troops fighting in Afghanistan can attest, NATO is not a talk shop nor a Renaissance Weekend on steroids.”
On a recent trip to Europe, Mr. Trump met with NATO members and left those talks in what he called “triumph,” after demanding that other countries contribute more money at a faster pace.
After Mr. Trump’s NATO meetings, he traveled to Helsinki where he met alone for two hours with Mr. Putin. During a joint news conference after the summit meeting, Mr. Trump appeared to capitulate to Mr. Putin, which drew outrage from many Republican lawmakers, longtime supporters and his aides.
Montenegro, once part of the former Yugoslavia, has become more western since the 1990s, much to the disdain of Moscow. The country of about 640,000 is not considered a military power. But Montenegro controls a strategic coastline where warships can dock between Gibraltar and eastern Turkey.