Washington (CNN) The 45th president entered office raging against a post-WWII order built by the United States, pledging instead that he would put "America First.

The US, President Donald Trump said during his campaign, could no longer afford to be the world's policeman. On the stump he also dismissed core alliances in Europe and Asia, raged at trade pacts, derided international organizations such as the UN and trash-talked allies (Mexico) and competitors (China) alike.

But since his inauguration, Trump has steadily reversed course on those fronts and a host of others.

The populist president has now embraced NATO, reaffirmed relationships with allies, reinforced international norms against chemical weapons use by bombing Syria and has sent more US troops to help rein in global conflicts.

Almost 100 days after Trump entered the White House dismissing the international system, Trump seems to be assuming a US president's traditional foreign policy role: being that system's biggest defender.

"It's a total 180," said James Jeffrey, a former US ambassador to Iraq and Turkey. "And to a certain degree, it's right."

Rhetoric hits reality

Analysts in Washington and overseas say a number of factors are at work, including the reality of dealing with global events, appeals from foreign leaders and the rise of experienced foreign policy mavens to Cabinet positions.

But some caution that the President, with no foreign policy experience, hundreds of unfilled national security staff positions and a reliance on equally inexperienced family members, is a reactive and tactical leader who still lacks a strategic vision -- preferring to disseminate his thoughts in 140-character bursts.

JUST WATCHED Trump's North Korean challenge Replay More Videos ... MUST WATCH Trump's North Korean challenge 03:12

They also point to the fact that many of the problems shadowing Trump's presidency in these first few months are tied to potentially compromising connections his circle has with global entities.

The FBI is investigating whether there was any coordination between the Trump campaign and Moscow while Russia was allegedly hacking Democratic organizations to benefit the Republican candidate during 2016. Trump's first national security adviser, retired Gen. Michael Flynn, had to step down after a controversial call with the Russian ambassador, while his work as a foreign agent during the transition has drawn scrutiny. Meanwhile, the Trump family still maintains myriad international business holdings.

Heather Conley, director of the Europe Program at the Center for Strategic and International Studies, said these ties should check the optimism of any observers who think Trump is adopting a reassuringly standard approach to foreign policy.

"We're comforting ourselves that this is normal and we should resist that view," she said.

Learning curve

Every president goes through a learning curve and Trump is no exception.

"There's no school for president," said Aaron David Miller, a former Middle East peace negotiator for the State Department now at the Wilson Center. "The issue for me is, is he learning? That's the key question."

Miller and Jeffrey pointed to the fact that Trump has surrounded himself with deeply experienced advisers, notably Defense Secretary James Mattis and national security adviser H.R. McMaster.

They "believe deeply in this system, and there's a reason we believe in this system, because the alternative is chaos," Jeffrey said.

Trump has shown a willingness to defer to them, Miller added.

Before his election, Trump backed torture. After taking office, he reversed course, saying Mattis had told him he'd always done better with "a pack of cigarettes and a couple of beers."

JUST WATCHED US Defense Secretary Mattis visits Afghanistan Replay More Videos ... MUST WATCH US Defense Secretary Mattis visits Afghanistan 01:26

Others, though, say giving them a seat at the table isn't enough.

"I'm heartened by the fact that he appears to be listening to the counsel of those people," said Christine Wormuth, a former undersecretary of defense in the Obama administration. "I would not go so far as to say I'm optimistic."

Her concern, she said, is that "it's not clear to me President Trump has a real strategic vision for the role the United States should be playing."

"I have a sense of what America First means to him in terms of trade, but trade is only one dimension of our foreign policy," said Wormuth, a senior advisor in the CSIS International Security Program. "It's one thing to say he wants better deals with this country or that country. What about problems outside the trade sphere?"

Military power

Trump has largely turned to the military to address global flashpoints, sending the USS Carl Vinson aircraft carrier near the Korean Peninsula last week, dropping the "Mother of All Bombs" on ISIS positions in Afghanistan on April 13 and sending Tomahawk missiles into Syria the week before.

At the same time, he's moving to drastically cut the State Department budget, Wormuth noted.

"Everyone is focused on the Tomahawk strike, the dust-up with North Korea," Wormuth said. "Those were tactical responses. Eventually the Trump administration is going to have to have an actual strategy and there's going to have to be a diplomatic component if we're going to have any real success."

Miller pointed to an ongoing Trump evolution in which "the realities of what it takes to campaign are giving way to the realities of governance, and that means adopting positions that are well considered and thought through."

He points to an early declaration that the US would move its embassy in Israel from Tel Aviv to the contested city of Jerusalem; the Trump campaign's dismissal of the Export-Import Bank; and the suggestion that Japan and South Korea develop their own nuclear weapons. All these positions seem to have quietly been abandoned.

JUST WATCHED Trump talks North Korea with Xi and Abe Replay More Videos ... MUST WATCH Trump talks North Korea with Xi and Abe 01:24

Earlier this month, Trump alluded to the difference between campaigning and engaging with the world. The President's most pressing security challenge may be North Korea, which is poised to conduct a sixth nuclear test in its increasingly aggressive pursuit of a nuclear weapon and the means to deliver it. Trump wants China to help with the challenge.

Trump wrote on Twitter over the Easter weekend, "Why would I call China a currency manipulator when they are working with us on the North Korean problem?"

Foreign leaders have also had some sway, said Jeffrey, particularly Israeli President Benjamin Netanyahu and leaders from Gulf countries like Saudi Arabia.

"The system has been very good to them," Jeffrey said of the global order, and they get "nervous" with a president "who comes in and disses the whole thing."

He continued, "They all march off to Washington and plead to him, 'Be the world's policeman,' and he agreed."

Coming around on NATO

Jeffrey believes the shift in Trump's view was reflected when Mattis, Vice President Mike Pence and Homeland Security Secretary John Kelly affirmed the US commitment to NATO at a German security conference in February.

"That's the moment when I think people started breathing a sigh of relief," Jeffrey said. "In that sense, it's a return to normal."

Others aren't yet sure. Miller pointed to Trump's mercurial character. "People don't fundamentally change," he said. "Can you keep your demons in check? It gets to fundamental questions of character."

Wormuth also questioned whether Trump can learn to be consistent: "Part of what's important in foreign policy is consistency and clarity in what you're communicating to your friends and enemies. Deploying unpredictabilty every now and then has value, but being seen by your allies as unreliable is dangerous."

Conley, of CSIS, said the damage is already done. "Our foreign policy used to be built on principles, the international trading order, international law, the security framework," she said. "When you shake those foundations, no one can rely on anything."

She pointed to the way longtime US allies are hedging, with Europe increasing its defense spending and Japan and Middle Eastern countries adjusting their defense posture and boosting arms purchases. The EU has made warmer overtures to China and issued a strategic document that stressed the need to lessen its reliance on the US.

Those alliances are "like a vase," Conley said. "Once broken, you can glue it back together, but it's never as strong as it once was."