President Donald Trump bombarded a NATO summit in Belgium with threats, undiplomatic rhetoric, confusion-sowing statements and false claims. Get ready, United Kingdom, you’re next. And he arrived with plenty of thoughts about Brexit. 

Trump has defended his unique style, which gives even some Republican lawmakers heartburn, by describing it as “modern-day presidential.” So what happened Wednesday and Thursday morning in Brussels might be labeled “modern-day diplomatic.”

But his approach is not going over well, at home or abroad. And that includes Capitol Hill, with Republicans worrying he is weakening a military bulwark against Russia and senior Democrats wondering if he is subservient to its president, Vladimir Putin, just four days before their high-stakes summit in Finland.

Watch: Ryan — Putin is ‘Not Our Friend’

This week has shown again the U.S. president’s wildly vacillating approaches to the job. It also has shown again how Trump can be his own worst enemy by following a positive with what are widely viewed as a string of negatives.

Consider that Trump on Monday night was measured and presidential when announcing his second Supreme Court nominee, Brett Kavanaugh. By Wednesday morning, however, he was ripping German officials, saying a pipeline deal with Russia makes the European country “captive” to and “totally controlled by” Moscow.

[Republicans Back From Russia Have Advice for Trump Before Putin Summit]

As the boss roared those charges, his chief of staff, John F. Kelly, and top envoy to NATO, former Texas GOP Sen. Kay Bailey Hutchison, grimaced and looked away in unison. Despite White House attempts to explain away their reactions, their unease was clear.

Then came his reported threats to leave NATO unless its other 28 members substantially increase their annual budgetary contributions. That was followed by a press conference during which he said the other allies had agreed to just that, and the statements were quickly — and remarkably — denied by French President Emmanuel Macron and NATO Secretary-General Jens Stoltenberg.

Lawmakers react

Republican senators such as Foreign Relations Chairman Bob Corker of Tennessee and others said Wednesday they agreed with the substance of many of Trump’s statements at the summit but not how he delivered them.

After Thursday morning, when Trump declared that Putin — whom U.S. intelligence agencies say oversaw an effort to interfere in the 2016 American election — was “not my enemy,” Democratic members had had enough of the president’s act.

House Minority Leader Nancy Pelosi said Trump’s behavior, including his actions at the NATO summit, beg the question of what Russia might have on him “politically, financially and personally.”

“The president’s behavior,” the California Democrat said, “is very curious.”

House Foreign Affairs ranking member Eliot L. Engel ripped into Trump on Thursday, saying he “tried to play the arsonist and the fireman at the NATO summit” by “nearly burning the alliance to the ground, then taking credit for extinguishing the fire he lit.”

“Frankly, his reckless behavior has hurt the alliance, undermined American leadership, and played into Russia’s hands,” the New York Democrat said. “Our allies did nothing but reaffirm commitments made four years ago at the Wales Summit.”

Those pledges were made in 2014, while Barack Obama was still president. Former President George W. Bush also called for alliance members to contribute more. But Trump refuses to acknowledge those facts, saying during a hastily arranged press conference Thursday that “nobody did anything about it” despite the 2014 pact.

‘Special’ visit

Trump left Belgium shortly after his impromptu press conference and landed outside London after a short flight. But he and first lady Melania Trump had to take a U.S. military helicopter for their trek to the American embassy in London.

White House aides used the term “special relationship” — first coined for the U.S.-British alliance in 1946 by Winston Churchill — nearly 10 times while briefing reporters late last week about the president’s U.K. visit.

Notably, however, the president repeatedly used the same term earlier this year: while Macron was visiting Washington, which Trump himself wanted to be the first state visit of his presidency. And while his aides tried to assure reporters that the U.S.-British partnership is as strong as ever, the president himself essentially told reporters to expect a repeat of the rocky and contentious NATO summit while he is on British soil.

“I’m going to a few hot spots. We have NATO, then we have the U.K., and then we have Putin,” he said, his arms straight out for effect. “Putin may be the easiest of them all. You never know.”

Then he took a thinly veiled shot at British Prime Minister Theresa May, who is under fire over her Brexit plan and after several of her Cabinet members abruptly left office: “But I’m going to a pretty hot spot right now, right? With a lot of resignations.”

The White House opted against the optics of the presidential motorcade traversing the streets of London amid protests about his very presence. But Trump, ever defiant, tried to brush off objections of many U.K. citizens to his visit and policies.

“Sure, there’ll be protests, because there are always protests,” he said in Brussels. “But I think … there were protests the night of the election, both ways.”

Back to 2016

Then the president launched into an unrelated — and false — retelling of history. He got his 2016 Electoral College count right, saying he got 306 votes. But then came the kind of claim that gives members pause.

[Marc Short Creates Another Void in the White House]

“One of the states we won, Wisconsin — I didn’t even realize this until fairly recently,” he said. “That was the one state that Ronald Reagan didn’t win when he ran the board his second time. He didn’t win Wisconsin, and we won Wisconsin. So you know … we had a great night.”

But that is incorrect. Reagan won the Badger State in 1980 and 1984.

The diplomat in chief, for some reason, then reminded the world he has property in Scotland, where he will spend the weekend, and “all over.” He then offered a preview of part of his message during Friday’s one-on-one meetings with May.

He said, without offering supporting data, that the British people “agree with me on immigration, and I think that’s why you have Brexit in the first place, because of immigration.” And though he pledged to let the U.K. government and European Union officials work out the specifics of the country’s departure from the group, Trump didn’t hold back Thursday.

He said he’s been “reading a lot about Brexit over the last couple of days,” noting he calculates that the U.K. could remain more economically tethered to European than first thought. Minutes after saying he had “no message” for his British counterparts on Brexit, he made his thoughts known.

“The people voted to break it up, so I would imagine that’s what they’ll do,” he said. “But maybe they’re taking a little bit of a different route. … I don’t know if that’s what they voted for.”

That single comment alone is enough to further complicate what once was a special relationship. Trump and May are set to address reporters together Friday afternoon. If the U.S. leader acts like, as Engel put it, “a bully, a bad friend and an unreliable ally,” things could get, to borrow a British term, bloody cheeky.

Lindsey McPherson contributed to this report.