In the late 19th century, circus barkers found that they could draw immense crowds by offering admission to sideshows, popularly known as freak shows, where paying customers could behold bearded ladies, two-headed dogs and other grotesques. That’s the attitude some members of the North Atlantic Treaty Organization (NATO) may have when they meet President Trump for the first time this week.

That’s understandable, given candidate Trump’s belligerent comments about NATO being “obsolete” and his empty threats to adjust America’s defense commitment to NATO countries based upon their increasing their defense spending.

The dedication this week of NATO’s sparkling new $1 billion headquarters in Brussels may be a source of European pride, but it also underscores Trump’s grousing that the alliance spends too much on frou-frous and not enough on defense. One other hitch: the building’s IT system hasn’t yet come online due to “technical difficulties.” This in an age of government hacking and data-theft.

“Trump’s campaign rhetoric alarmed the allies,” says Alexander “Sandy” Vershbow, a former U.S. ambassador to NATO as well as Russia. “Since his election, he’s said that NATO is no longer obsolete. So their worst fears have not been realized. But there’s still some anxiety that the conversion of the president could just be temporary.”

Trump could use the summit in Brussels to try to ease those fears. Then again, this quixotic U.S. president may decide that now is the time to press for a reconfiguration of the 68-year-old defense alliance, which was cobbled together as a bulwark against an aggressive post-World War II Soviet Union.

“I’m not sure the U.S. needs to, or should, keep the leading role in NATO that it traditionally has had,” says Doug Bandow, a senior fellow at the CATO Institute, a libertarian think tank. Speaking at a conference hosted this week by the Center for the National Interest, Bandow underscored Trump’s complaint that America’s European allies are not paying their fair share of the NATO budget. Says Bandow: “Europe won’t act as long as it believes it can rely on the U.S. to defend it.”

While the United Kingdom (still a NATO member despite Brexit) and Poland exceed their mandated two percent of GDP on defense spending, key members like France, Germany, Italy and Spain are well below that benchmark, and are dragging their feet at meeting their commitment. Baltic member states like Latvia and Lithuania, which fear Russian aggression in their direction, have pledged to meet their goals, but as yet, have not.

Trump, who has said he wants to improve relations with Moscow, will have to decide whether he even wants to remain a strong voice within an alliance whose main purpose now is to keep Russia at bay. There are reasons he should, among them, the 2014 annexation of the Crimea from Ukraine. That demonstrated that President Vladimir Putin will seize opportunities, even those that flout international law, if he smells weakness from the West.

Recommitting the U.S. to its European allies will make the orange-haired American seem more like a member of the club, and less like a circus curiosity.