Washington (CNN) Donald Trump's exit from the Iran nuclear deal was one of the most significant moments of his presidency -- and cemented a sharp turn in decades of US foreign policy orthodoxy.

It also opened a new window into Trump's political soul, showing his willingness to unleash the kind of chaos abroad he has fomented at home.

The decision added context to his "America First" foreign policy doctrine and showed he is adamant about following through on campaign promises that horrified America's allies.

And it revealed two other pillars of the Trump presidency -- a propensity to turn even the most crucial moments into a global televised drama, and his ravenous desire to eradicate President Barack Obama from the history books.

Trump is the 'no Plan B' president

The most frequently heard criticism of Trump's decision was that he was pulling out of the deal without offering a plan for what will happen next.

"No one has any clue on the day after. There is no strategy," a senior European diplomat told CNN's Michelle Kosinski, describing the State Department as "a shambles."

But if anyone is shocked, they have missed Trump rolling the dice over the last 16 months.

The President fires people before he finds replacements, makes up policy on the fly, decided to meet North Korean leader Kim Jong Un seemingly on a whim, and slashed away at Obamacare without offering a replacement.

His legal gambits seem to come off the top of his head -- with or without Rudy Giuliani

He follows his gut, doesn't sweat the details and thinks he's his own best adviser. He breaks things and sees where the pieces land.

His response when asked how dangerous global crises will end is "we'll see" -- an attitude that reflects his unpredictable nature and often misplaced confidence he can control careening events.

So what Trump did Tuesday should have come as no surprise. Pulling out of an Iranian nuclear deal without knowing how Tehran or America's allies will react or if global tensions will spike or if oil prices will surge is consistent with who Trump is.

His team could not say what they would do if Iran resumed enriching uranium or if there was a schism in the transatlantic relationship.

"We did not talk about a Plan B," a senior State Department official said.

If 'America First' means America alone -- so be it

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In Davos in January, Trump said that "America First does not mean America alone." That is no longer a credible statement.

Trump surely lost no sleep by unilaterally violating an international nuclear agreement endorsed by the UN Security Council -- the chance to go it alone was likely a selling point.

To purge his antipathy to the deal, Trump split with America's European allies, France, Britain and Germany, leaders of which had all but begged him to stay in.

It was a sign that traditional alliances are less important to Trump than to any President of the post-World War II era, and shows that loyalty to friends, as in his personal and political life, cuts only one way. After all, only two weeks ago he was kissing and holding hands with Emmanuel Macron during the French President's charm offensive.

Trump's administration is already trying to bully allies: new ambassador to Germany Richard Grenell tweeted Tuesday: "As @realDonaldTrump said, US sanctions will target critical sectors of Iran's economy. German companies doing business in Iran should wind down operations immediately."

As @realDonaldTrump said, US sanctions will target critical sectors of Iran's economy. German companies doing business in Iran should wind down operations immediately. — Richard Grenell (@RichardGrenell) May 8, 2018

It was not the first time that Trump rejected multi-lateral solutions to the world's problems.

He pulled out of the Trans-Pacific Partnership trade deal and the Paris climate accord. He's torn at the system of international trade with disputes with China, Canada, Mexico and South Korea.

Trump clearly doesn't care what foreign elites and national security experts think -- his decision to move the US embassy in Israel from Tel Aviv to Jerusalem is evidence of that.

That was his appeal to his voters and he's sticking with it.

Tuesday's move also shows that he's throwing in his lot with Middle East allies, such as Saudi Arabia and Israel, who want to crank up military and diplomatic pressure on Iran.

But he's also rejecting what much of Washington sees as America's global role.

"We are giving up our global leadership ... and I'm concerned, as are many of my colleagues," GOP Sen. Jeff Flake told CNN's Jake Tapper

But to Trump, leadership means he leads and the rest of the world follows.

Whether that is a credible basis for American diplomacy will be one of the most important questions answered by the rest of his presidency.

Trump keeps his promises

The President vowed to ditch the Paris deal and the TPP -- he did. He was against the Iran agreement even before he was a candidate and ended US participation.

Tuesday's decision was a reminder that nothing is as important to Trump as keeping faith with his supporters even if it means sparking global disruption.

It's not just a matter of honesty, it's about political survival since he has made little effort to reach beyond his base and needs huge turnouts to stave off the threat of a Democratic takeover of the House in November and to keep his job in 2020.

Of course, there are plenty of promises that Trump didn't keep. He vowed to build a health care system for everyone better than Obamacare, but has done little but undermine his predecessor's namesake law. His tax cut does far more for the wealthiest Americans than the blue collar voters he vowed to help.

Still, Trump will use his withdrawal from the Iran deal to convince his voters that he will never shatter the bond they share.

Facts don't seem to matter

The Iran announcement was quintessentially Trumpian.

He misrepresented the restrictions imposed by the Iran nuclear deal and suggested, against the testimony of his own intelligence agencies, that the Islamic Republic was already violating it.

For instance, he said that Iran was continuing to enrich uranium that would allow it eventually to build a bomb.

But under the deal, Tehran can enrich limited quantities of uranium up to 3.67% -- well below the 90% weapons grade uranium needed to build a bomb.

He also used Israeli intelligence about Iran's historic pursuit of the knowledge to make nuclear weapons to suggest to Americans not familiar with the deal that Tehran was not in compliance.

Trump also created his own alternative reality to suggest he would bring Tehran rushing back to the table begging for a deal that would be better for America.

"The fact is they are going to want to make a new and lasting deal. One that benefits all of Iran and the Iranian people," Trump said.

Given that America's European allies, and Russia and China plan to stick with the existing deal, leverage -- made of punitive multilateral sanctions -- that got Iran to the table during the Obama administration could be elusive for Trump.

Trump really hates Obama

It has been a reliable guide to the President's actions -- if Obama was for it he is against it.

Foreign diplomats said privately that one reason Trump hates the Iran deal was that it was the proudest foreign policy achievement of the Democratic president.

"I hope that Americans continue to speak out in support the kind of strong, principled, fact-based and unifying leadership that can best secure our country and uphold our responsibilities around the globe," he wrote.

It was a clear shot at Trump's method and character as he joined a battle between the legacies of the 44th and 45th presidents that will echo long after they are both gone.

Trump the showman

Trump loves to be the star of the show.

He has welcomed pleading foreign leaders to his court and drip, drip, dripped tantalizing details about his decision on Iran for weeks.

He gathered himself behind the presidential podium on Tuesday, squaring his jaw and staring into the camera with the world on tenterhooks, relishing his leading role.

And as he wrapped up one long-running drama, he set the stage for his next, even more spectacular moment.