London (CNN) At the outset of NATO's 70th anniversary meeting, which was meant to promote the unity of the alliance, no one doubted President Donald Trump's ability to disrupt, and he didn't disappoint , taking his tactics to a new level.

Trump laid into two leaders who theoretically should be among the US's closest allies, dissing French President Emmanuel Macron by calling his comments about NATO experiencing "brain death" "very insulting" and confronting Canadian Prime Minister Justin Trudeau by demanding he say how much Canada spends on defense and calling him "two-faced."

It was in some ways a masterclass in disregard for the normal rules of diplomacy, which is traditionally conducted through skilled and subtle conversations behind closed doors.

Of course, Trump's bombastic approach is no surprise to Americans, who in near equal measure applaud or are appalled by their leader.

But in Europe, where object lessons in Trumpism are infrequent, this visit has underlined that there is no magic formula or silver bullet to get what you want out of Trump.

Macron has tried it all, from bromance a few years ago to confrontation this week. Germany's Angela Merkel, who was never an over enthusiastic engager with Trump, now does passive like a possum does dead. The result is still the same: Trump does what Trump wants.

At times he has appeared out of his depth, or plain confused. He was the only leader during the handshake greeting ceremony not to understand the cues and try to walk the wrong way offstage.

Tussle with Macron

Maybe that was an easy mistake -- we've all been there -- but he just didn't seem to keep up with the dialogue at times. Strikingly, when he challenged Macron to take ISIS fighters back to France he was told to get serious.

"Would you like some nice ISIS fighters? I could give them to you. You could take every one you want," Trump asked.

"Let's be serious," Macron said before pushing back. "The number one problem are not the foreign fighters. This is the ISIS fighters in the regiment and you have more and more of these fighters due to the situation today."

Trump replied dismissively, "This is why he's a great politician. That was one of the greatest non-answers I've ever heard. And that's OK."

The trouble was Macron had not only answered, but he'd also answered the President back. Either Trump didn't understand or he was bluffing to cover Macron's put-down.

It wasn't Trump's only clash. On Wednesday he called his Canadian neighbor Trudeau "two-faced."

There is an irony in this that may well be lost on the US President, who has clearly shown two distinct sides to his character this week.

Marked change day by day

On day one, the exuberantly confident world leader was ready to take any question, loquacious in the extreme with his generous answers.

Then on day two, he'd morphed into a taciturn politician, delivering tight, terse answers. To paraphrase another leader, Queen Victoria, whose empire was also on the verge of tipping toward decline, Trump was "not amused" by the second day of the meeting.

Any doubt his clipped conversations could have another meaning ended with the cancellation of his planned end-of-meeting news conference.

Maybe he had given too much of himself Tuesday: 52 minutes of reporter Q and As with NATO Secretary General Jens Stoltenberg, followed by 41 minutes with Macron and then 35 minutes with Trudeau. More than two hours total.

Perhaps Trump was simply tired and wanted to go home, but that is not the impression he leaves behind. He seemed angry and unhappy, and the person he focused that displeasure on was the Canadian Prime Minister.

He was reacting to a few moments of viral video where Trudeau was caught on camera joking with British Prime Minister Boris Johnson, France's President Macron and Holland's Prime Minister Mark Rutte, apparently at Trump's expense.

They were inside Buckingham Palace, had just met the Queen but were quite clearly in a rare moment of reverie discussing their experiences with Trump.

Trudeau was explaining the reaction of Trump's team to their President during their meeting, saying, "You just watched his team's jaws drop to the floor" as the President announced the next G7 summit will be held at Camp David, rather than Trump's Florida Doral resort outside Miami.

Trump's character flip is what makes it hard for allies to do meaningful business with him; it's why this meeting was a leaders' meeting, not a summit, as NATO's annual gatherings are usually dubbed,

The title change obviated the need for a communique, and therefore compromise and a meeting of the minds. It was replaced by a joint declaration that was simply a rehash of NATO goals updated with some new numbers reflecting increased defense spending by NATO members.

It was these figures that Stoltenberg had hoped might please, even pacify, Trump. A $130 billion increase in defense spending by the US's NATO allies since 2016, with nine nations now meeting NATO's threshold of a 2% of gross domestic product spend on defense, up from three in 2016.

Yet even with these figures, Trump could not contain himself: $131 billion, he said several times, he just had to amp it up. Then he stepped over the line, claiming it was $130 billion a year, which was not what NATO was saying.

Warping the facts

It was not the only example of his warping facts to fit his agenda.

He said he has once been angry with NATO but as a result of the increased spending and "flexibility" he lavished praise on Stoltenberg.

And then he did what he does, bending the truth again, claiming NATO had become more flexible since he came to office, that It was branching out and becoming more international -- and implied that was a result of his efforts.

The fact is the whole point of NATO is that its members have each other's backs, and the only time all NATO members have ever been called by one member to come to its aid under NATO's Article 5 was to help the US after the 9/11 terror attacks in 2001.

So yet again Trump didn't disappoint. In his own unorthodox way he might even have exceeded expectations.

He disrupted, then departed, cementing his reputation as mercurial, leaving his allies united only in their realization that this is as good as it gets with Trump, and NATO's long-term goals and vision are on hold for another year.