To understand how the political sands have shifted since U.S. President Donald Trump ordered Thursday's military strike in Syria, don't just pay attention to the rare praise he's getting from Capitol Hill.

Watch the outrage he's stirring up among his former fans in the alt-right, the anti-immigrant fringe movement that embraces white supremacy and isolationism.

While lawmakers best known for challenging the president gushed about his decision-making, prominent white nationalist Kevin MacDonald was at home fuming.

"It's a betrayal," the editor of the "white identity" journal The Occidental Observer said from California on the morning after Trump's decision to launch dozens of Tomahawk missiles at a Syrian airbase.

The alt-right has been alienated, MacDonald said in a phone interview.

"I'm concerned now this whole administration is going the way of the neocons. The whole nine yards," he said. "I'm very disappointed; very agitated."

I guess Trump wasn't "Putin's puppet" after all, he was just another deep state/Neo-Con puppet.<br><br>I'm officially OFF the Trump train. —@PrisonPlanet

The swift American military offensive was intended to punish Syrian President Bashar al-Assad's regime for unleashing deadly chemical weapons on scores of women and children earlier in the week. But the U.S. attack offended the anti-globalist principles of the far-right elements drawn to Trump's "America First" rhetoric.

'That's it. I'm done'

Some of Trump's staunchest anti-war allies in the libertarian and far-right communities have now spurned him. They say the military intervention in Syria showed Trump was never the true isolationist they hoped he'd be.

As some alt-right online commentators saw it, their anti-establishment candidate caved to status-quo political pressures.

"That's it. I'm done. Trump is a cuckservative now," wrote one user on the 4chan "Politically incorrect" message board, using the derogatory alt-right epithet for an effete, moderate conservative.

"Trump is a puppet now," another 4chan user wrote on the same thread discussing the missile strike. "Swamp drowned him."

A screengrab from the 4Chan message board's 'Politically Incorrect' forum shows users complaining about Trump's missile strike.

As with MacDonald, who has been described by the Southern Poverty Law Center as "the neo-Nazi movement's favourite academic," some of Trump's most dedicated admirers in the alt-right were stunned by the news. Trump's missile strike aligned with what his former Democratic rival for president, Hillary Clinton, had suggested Thursday, when she told a women's forum she would "take out" Assad's airfields.

The president, MacDonald thought, was supposed to be an "America First" leader focused on a non-interventionist foreign policy.

"That was one of the things we in the alt-right liked," he said.

Richard Spencer, who coined the "alt-right" term, expressed his displeasure in a video he titled "The Trump Betrayal." Alex Jones, the conspiracy theory pedlar and host of InfoWars, said on his show Trump was "disintegrating in my eyes."

And Milo Yiannopoulos, the former Breitbart editor and political agitator who once co-authored a manifesto on the alt-right, wrote on Facebook: "There comes a day in every child's life when his Daddy bitterly disappoints him."

MacDonald said he would consider "jumping off the Trump train," but plans to hang on despite his "faith being on shaky ground."

"The Trump Betrayal"<br><br>My video on Trump, Syria, and the end of "America First."<a href="https://twitter.com/hashtag/nowarwithsyria?src=hash">#nowarwithsyria</a> <a href="https://t.co/2qZ3TyyqOX">https://t.co/2qZ3TyyqOX</a> —@RichardBSpencer

Beyond the Syrian intervention, MacDonald said the past week has troubled him because of reports about former Breitbart chairman Steve Bannon being booted from Trump's National Security Council. It sounded to him like a demotion for Bannon, an alt-right godfather of sorts, in favour of Trump's more moderate-leaning son-in-law, Jared Kushner.

"Bannon's being pushed aside a little bit [by] Jared Kushner," MacDonald said, slamming Kushner as "a globalist."

"Meanwhile, Trump kept the neocons out of this administration, but he's being applauded now by the neocons for what he's doing in Syria."

A Syrian child receives treatment at a small hospital in the town of Maaret al-Noman following a suspected toxic gas attack in Khan Sheikhun, a nearby rebel-held town in Syria's northwestern Idlib province, on April 4. (Mohamed Al-Bakour/AFP/Getty Images)

Matthew Lyons, who has researched the origins of the alt-right and co-authored the book Ctrl-Alt-Delete: An Antifascist Report on the Alternative Right, said far-right groups will see Trump's Syria strike as a "dramatic abandonment" of his stated foreign policy doctrine.

"If Trump continues in the same vein, I think it probably will mean a pretty definitive break," Lyons said.

Shaking up alliances

Whatever divisions the Syria development has caused may also just be temporary, suggested Julian Zelizer, a professor of American political history at Princeton University. Military conflict often has the potential "of shaking up entrenched political alignment and alliances," he said.

"So friends become enemies, and vice versa. That's what you're seeing with the far-right getting angry with Trump."

There was certainly some jarring messaging coming from ordinarily cantankerous senators who have made a habit of criticizing the president. There was a new tone, for instance, from Republican senators Lindsey Graham and John McCain following the strike against Assad's regime.

John McCain, a Republican senator who is often critical of Trump, spoke out in support of his missile strikes against Syria. (J. Scott Applewhite/Associated Press)

"I was very proud of him," Graham said, before reportedly comparing Trump to a conservative presidential icon.

"I think there's a side to President Trump that's very much like Ronald Reagan," Graham said, according to the Washington Post's Dave Weigel.

More Graham: "I said, I was very proud of him. He said a lot of people had called, 100 countries had called the White House and thanked him" —@daveweigel

Trump "took action" by striking Assad's airfield, McCain said. "For that, he deserves the support of the American people."

Bill Kristol, the conservative editor of The Weekly Standard and an avowed #NeverTrumper, joined the Trump love-in, tweeting that "a growth spurt" in the president's leadership appeared to be underway.

If Pres. Trump takes appropriate action against Assad this <a href="https://twitter.com/hashtag/NeverTrumper?src=hash">#NeverTrumper</a> will of course support him. He's the president, not merely "Trump." —@BillKristol

Democrats also endorsed the attack. House minority leader Nancy Pelosi did so publicly but with a caveat: the use of military force, she argued, should have been authorized first by Congress.

"I'm supportive of the Trump administration's decision to launch airstrikes in response to Assad's assault on his own people," wrote Senator Jeanne Shaheen.

Chuck Schumer, the Democratic Senate minority leader, described the action as "the right thing to do" in his written statement.

Senate minority leader Chuck Schumer said the U.S. attack was 'the right thing to do.' (J. Scott Applewhite/Associated Press)

As for Trump's base?

"Wait for the polls. My instincts say they will be delighted," said congressional expert Ilona Nickels. She said more moderate Trump conservatives may view him as a "man of action" versus "the cerebral paralysis of Obama," who was criticized in 2013 for apparently pulling back on a decision to launch a military strike against Syria.

Zelizer, the Princeton professor, expects traditional partisan divisions to settle once the battle lines are no longer fresh. After the Sept. 11, 2001, attacks, for example, a period of goodwill and bipartisanship lasted about a month.

"As Congress started to think of key issues and people started thinking about elections, the divisions re-emerged," he said. "The question now is will these divisions continue? For how long? And do people go back to where they were before the missile strike?"