In the dozen years since it broke away from Serbia, Montenegro, a scenic little country on the Adriatic with fewer than seven hundred thousand people, has probably never had so much attention. On Tuesday, the Fox News anchor Tucker Carlson asked President Trump why, if Montenegro were attacked, his son should have to go defend it. Montenegro is the newest member of NATO; it just marked one year of membership. “I’ve asked the same question,” the President replied. “Montenegro is a tiny country with very strong people. They’re very aggressive people. They may get aggressive, and, congratulations, you’re in World War Three.”

Fresh off his NATO summit, President Trump somehow still does not know the basic idea behind the world’s most powerful military alliance—or much about geography, either. First of all, Montenegro is far from being aggressive. Its army only has one thousand nine hundred and fifty active-duty members. Yet it has deployed troops to support the NATO mission in Afghanistan since 2010—seven years before it gained membership in the Western alliance. The President also apparently does not read statements sent out in his name. In April of last year, after the U.S. ratified Montenegro’s membership, a White House release stated, “President Trump congratulates the Montenegrin people for their resilience and their demonstrated commitment to NATO’s democratic values.”

Trump’s comment sparked both bewilderment and outrage. “I have no idea where Trump gets the idea Montenegro is ‘very aggressive,’ ” Ivo Daalder, a former U.S. Ambassador to NATO and now the president of the Chicago Council on Global Affairs, told me. “It’s been independent twelve years and never even came close to starting any war. In fact, two years ago, months before Montenegro would accede to NATO, a Moscow-backed coup attempt sought to prevent it from joining the alliance. If there’s been aggression, it’s come from Moscow, not Montenegro.” The failed coup was a Russian effort to prevent Montenegro, once a part of communist Yugoslavia, from aligning with the West.

Senator John McCain, the Arizona Republican, tweeted a scathing rebuke of Trump for playing into the hands of Russian President Vladimir Putin—again. “The people of #Montenegro boldly withstood pressure from #Putin’s Russia to embrace democracy,” McCain wrote. “The Senate voted 97-2 supporting its accession to #NATO. By attacking Montenegro & questioning our obligations under NATO, the President is playing right into Putin’s hands.”

During his interview with Trump, Carlson phrased his question correctly in terms of what joining NATO means. “Membership in NATO obligates the members to defend any other member that’s attacked,” Carlson told Trump. The President then showed his ignorance about NATO’s mission—and the difference between defense and offense—by suggesting that the United States would have to back Montenegro if it launched a military offensive. (It’s an unlikely prospect anyway, given its size—smaller than Connecticut—and population.)

“NATO is a defensive alliance. It always has been,” Douglas Lute, a former three-star general, Ambassador to NATO, and National Security Council staffer in both the George W. Bush and Obama Administrations, told me. “If one of the member states is the target of an armed attack, then the others are obliged to come to its assistance. There’s no obligation to support offensive operations.”

NATO has invoked Article 5 of its treaty only once—after the September 11, 2001, attacks in New York and Washington. “As part of their obligation, members of the alliance came to our assistance, and that plays out today, including by small countries like Montenegro,” Lute said. The war in Afghanistan—America’s longest foreign war ever—rages on, with sixteen thousand NATO personnel still involved. In contrast, the U.S. war in Iraq was an offensive initiative that NATO did not have to support—and didn’t.

Nicholas Burns, a former U.S. Ambassador to NATO, called Trump’s comments “reckless and ill-informed” and said they cast doubt on the U.S.’s willingness to lead the alliance. “Deterrence against a potential aggressor works when the credibility of the U.S. is clear and strong,” Burns told me. “Trump has now muddied the waters with his deeply unfortunate comments. He is playing into Putin’s hands. Putin wants to divide the U.S. from its allies and to weaken NATO.”

Of the thirteen Presidents who have embraced NATO—as it has grown from twelve nations, in 1949, to twenty-nine nations today—Trump’s commitment is “by far” the weakest, Burns told me. “I fear he is damaging both American credibility and the NATO alliance.”

Trump’s remarks follow the tense annual NATO summit in Brussels last week, where he insulted the German Chancellor and demanded that NATO members at least double their defense spending. “What his off-the-cuff comment reveals is that he really does doubt the value of NATO,” Lute said. “Despite his claims to the contrary, this reveals a deep doubt and deeply held suspicion of the value of the alliance and Article 5.”

The President’s insult to Montenegro is not the first. Last year, Trump was caught abruptly elbowing aside the Montenegrin Prime Minister, Duško Marković, when the leaders of NATO countries assembled for a group photograph. He did not acknowledge Marković—or apologize. The video went viral.

The feeling is mutual among some Montenegrins. I visited the mountainous country in May, 2016, as the U.S. election was heating up. One afternoon, I walked up a rock-strewn path to the Church of Our Lady of Remedy, which dates back to the sixteenth century. The site offers a breathtaking view of the Bay of Kotor. On the way up, I had to buy a ticket for access to the area. As I handed over five euros, the young ticket taker asked, “Are you American?”

“Yes,” I replied.

“Please,” he told me. “Don’t vote for Donald Trump.” That sentiment has almost certainly increased since the President suggested Montenegro could start a third world war.