WASHINGTON - Donald Trump's sudden embrace this week of a nuclear arms race - and his staff's scramble to minimize the fallout - underscored an emerging modus operandi for the president-elect: governance by chaos.

Since winning the election, Trump has seemed to revel in tossing firecrackers in all directions, often using Twitter to offer brief but provocative pronouncements on foreign and domestic policies alike - and leaving it to others to flesh out his true intentions.

In the past week alone, Trump has publicly pitted two military contractors against one another, sowed confusion about the scope of his proposed ban on foreign Muslims, and needled China following its seizure of a U.S. underwater drone.

But nothing has created more consternation for many foreign policy experts than Trump's assertion on Twitter on Thursday that the country should "greatly strengthen and expand" its nuclear capability.

On Friday, after his staff had tried to temper his comments, Trump doubled down, telling a television talk-show host that in an arms race against any competitor, the United States would "outmatch them at every pass."

Trump has pledged to shake up both Washington and the world order, and boosters argue that a degree of unpredictability can be useful, particularly when it comes to foreign policy. But the mixed messages and erratic nature of his pronouncements have alarmed even some Republicans, who say it's important to know how seriously to take the leader of the free world.

"We're just operating in this world where you cannot believe the things he says," said Eliot Cohen, a foreign policy expert and former George W. Bush administration official at the State Department. "It will have large consequences for our allies and our adversaries, and it's going to greatly magnify the danger of miscalculation by all kinds of people."

Trump's team has struggled with the new resonance that becoming president-elect has given Trump's Twitter habit. They have repeatedly said that his statements on social media do not necessarily reflect his official policy and have at times sought to play down the import of his actions.

But Trump supporters say the rest of Washington is going to have to get used to his more freewheeling style.

"People who expect the past are going to be shocked that there's a new way of doing things," said Barry Bennett, a Republican strategist who served as an adviser to Trump during the general-election campaign. "This is a glimpse of where he's headed, and in a way, it's highly transparent, but just not the way Washington has done business for the past 40 or 50 years."

But others warn that Democrats and Republicans alike on Capitol Hill could have a hard time reading Trump and discerning his true priorities if he continues to operate as he has during the transition.

"It's difficult to separate the wheat from the chaff - what comes out that he really wants and what's just said at the spur of the moment," said Jim Manley, a former longtime aide to Senate Minority Leader Harry Reid (D., Nev.). "In the past, a president-elect doing something like this would have been unfathomable."

The imbroglio over nuclear arms began Thursday with a tweet from Trump in which he said the United States "must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes."

Trump made no mention of what spurred his thoughts, but the tweet followed an address by Russian President Vladimir Putin in which he said his country's nuclear stockpile needs fortifying.

Trump's tweet seemed to signal a break with four decades of policy charted by presidents of both parties - and it sent his staff scrambling to explain his thinking.

In a television interview Thursday night, Kellyanne Conway - named counselor to the president earlier in the day - downplayed its sweep.

"He's not trying to change a policy through Twitter," Conway told MSNBC's Rachel Maddow. "What he's merely saying is that he wants us to be ready to defend ourselves."

Conway said Trump's tweet was not necessarily aimed at Russia but directed at "a regime that would do us harm or a rogue nation."

Trump was not backing down Friday morning, however. On MSNBC's Morning Joe, cohost Mika Brzezinski relayed a conversation she had with Trump in which he reportedly said, "Let it be an arms race. We will outmatch them at every pass."