BRUSSELS — President Donald Trump has picked on some seemingly unlikely targets around the world of late: Canadian Prime Minister Justin Trudeau, British Prime Minister Theresa May and German Chancellor Angela Merkel.

All three are more-or-less establishment figures running Western democracies that have long been allied with the U.S., and yet Trump seems bent on treating them more like adversaries.

Trump called Trudeau "dishonest" and "weak" last month. He has opted not to offer support for May so far this week as her government teeters on the brink of dissolution. And on Wednesday, he called Merkel's Germany a "captive of Russia" — a reference to the Nord Stream II gas pipeline project that has drawn criticism from Merkel's political left and right.

If ever there was a chance for Trump to tilt the balance of global power toward conservative nationalism and away from the old liberal democratic order, this week is it. And by trashing Germany and questioning the value of the North Atlantic Treaty Organization on Wednesday, Trump suggested he’s all in on taking a hammer to the latter.

His criticism of Merkel could embolden her right-wing domestic adversaries at a time when she's been weakened by a fight over immigration policy, and even a modest push from Trump could help topple May and deliver her job to a Tory who is more committed to isolating Britain from the European Union. While Trudeau is hardly in a precarious position, he is slowly but surely getting lonelier as the leader of a major democratic nation committed to international economic and defense accords.

After sitting down with Merkel Wednesday — and after launching his visit here by tearing into Germany over both the pipeline and its failure to hit a NATO target for defense spending — Trump is due to meet with May Thursday and Friday in the U.K. He has said her political fate is "up to the people."

Presidents have been trying unsuccessfully for years to get Germany and other rich NATO Nations to pay more toward their protection from Russia. They pay only a fraction of their cost. The U.S. pays tens of Billions of Dollars too much to subsidize Europe, and loses Big on Trade! — Donald J. Trump (@realDonaldTrump) July 12, 2018

....On top of it all, Germany just started paying Russia, the country they want protection from, Billions of Dollars for their Energy needs coming out of a new pipeline from Russia. Not acceptable! All NATO Nations must meet their 2% commitment, and that must ultimately go to 4%! — Donald J. Trump (@realDonaldTrump) July 12, 2018

But it probably isn't — and Trump probably knows that. May's most immediate problem is a push from within her own party to sack her with a no-confidence vote among party caucus members. If someone — perhaps just-resigned Foreign Minister Boris Johnson — can put together the votes to succeed her, May could be gone within a matter of weeks.

Her crime, in the eyes of national populists: Trying to engineer a softer exit from the E.U. than many of her colleagues wanted. Now her wisdom and judgment are being questioned not by the opposition Labour Party, but by fellow conservatives in the U.K. and around the world.

"Trump's visit couldn't come at a worse time for May," one U.S. source with ties to U.K. conservatives said, adding that there is a "big push" to dump her.

Trump could show a sign of support for May, or refuse to take her side — or even possibly become an active part of the movement to replace her. Anything less than a full-throated endorsement would naturally be taken as a sign that Trump doesn't favor her remaining in power.

And, so far, he has withheld such an endorsement.

At the same time, Trump is eager to sit down with Russian President Vladimir Putin, a nationalist leader upon whom Trump has showered praise in the past. Rather than friend or foe, Trump has characterized Putin as a "competitor" in the international arena — even after Russia meddled in the 2016 election and even as Trump administration officials and members of both parties in Congress say Russia is continuing to try influence future elections.

Trump isn't just cozying up to a longtime foe and giving the cold shoulder to staunch allies. He's also making life difficult for leaders who have stood in the way of the conservative nationalist politics that have swept Europe and the U.S. over the last several years.

Now, with his up-close look at May imminent, the question is whether Trump will follow through in helping like-minded conservatives take her out or whether he will prevail on them to back down. It's hard to see him risking political capital to help save her, which suggests just how much peril she's in.

Trump prizes disruption — sometimes for its own sake — and promotes nationalism around the globe. There may be no simpler expression of those goals than bludgeoning members of an alliance for not spending more money building their own militaries.