President-elect Donald Trump is alarming critics by not only threatening to dispatch with political correctness but also disregarding the basic tenets of world order surrounding nuclear weapons.

With a single tweet Thursday and then a follow-up chat with a television broadcaster on Friday, Trump entered the holiday weekend shaking up global affairs by stating an interest in vastly expanding the U.S. nuclear arsenal, even if it means restarting an arms race with Russia.

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While Trump’s statements so far lack much by way of detail, his staff have tried to walk them back, and he also hasn’t said how he’d get a Republican-controlled Congress to go along with him. The president-elect has nonetheless alarmed skeptics who warn of a possible major reversal ahead on decades-old U.S. nonproliferation policy.

“This form of nuclear saber rattling could represent the most dangerous turn in global nuclear weapons policy since the end of the Cold War,” said John Tierney, a former Massachusetts Democratic congressman now serving as executive director at the Center for Arms Control and Non-Proliferation.

Tierney called on Trump to “immediately disavow his own statement for the sake of U.S. and international security.”

Trump’s top staffers have been trying to parse their boss’s remarks since his initial tweet Thursday afternoon stating the U.S. “must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes.”

Kellyanne Conway, the incoming White House counselor, said during an MSNBC appearance Thursday night that Trump was “not making policy on Twitter” and she tried to clarify that he was talking about modernizing the nuclear arsenal, rather than increasing its size.

But Trump further muddied the matter on Friday, telling MSNBC “Morning Joe” co-host Mika Brzezinski during an off-camera interview, “Let it be an arms race…we will outmatch them at every pass and outlast them all.”

Team Trump did try to tamp down some of the controversy later Friday by releasing a two-week old holiday letter from Russian President Vladimir Putin that described U.S.-Russian relations as an “important factor in ensuring stability and security of the modern world.”

But Trump in an accompanying statement also included a warning: “I hope both sides are able to live up to these thoughts, and we do not have to travel an alternate path.”

Putin also has helped kindle the controversy. Earlier this week, he said Russia would “need to strengthen the military potential of strategic nuclear forces, especially with missile complexes that can reliably penetrate any existing and prospective missile defense system.”

But on Friday Putin said during his annual news conference that Russia wasn’t interested in a nuclear arms race.

Taken together, the Trump and Putin statements have left many nuclear experts scratching their heads, and for good reason. After all, the 2016 presidential campaign did conclude with U.S. intelligence agencies blaming Putin’s government for carrying out cyberespionage against Democrats with a goal of helping Trump win the election.

Many experts raising alarm over a possible Cold War redux say that it’s especially troubling to have the chaos happen before Trump takes office, and to be inflamed by a social media feed that the Republican used to such great effect during his campaign.

In addition, they fret that the strategy Trump used with considerable success on the campaign trail of shaking up traditional norms can have real-world consequences when inserted into something as multi-dimensional as foreign policy and nuclear weapons.

“It’s a message to the other countries to start their engines,” Joseph Cirincione, president of the global security foundation’s Ploughshares Fund, told MSNBC on Friday.

Jim Walsh, an MIT international security expert, said Trump doesn’t “understand that these pronouncements have unsettling implications for our allies, the nonproliferation regime and for American treaty commitments.”

“Using Twitter to blurt out ill-conceived changes to U.S. nuclear weapons doctrine is unwise if not downright dangerous,” he added.

Democrats tracking the Trump nuclear flap said they’re not surprised by the latest wrinkle. “Don't write this off as just Trump being Trump – he has been consistent about his desire for more nukes in the world,” the Democratic National Committee said in a press release drawing attention to Trump’s 2016 campaign statements where he declared an interest in using nuclear weapons and also in seeing their development by U.S. allies, including South Korea, Japan and Saudi Arabia.

So far, Republican leaders including Speaker Paul Ryan, House Foreign Affairs Chairman Ed Royce and Senate Foreign Relation Chairman Bob Corker have stayed silent on Trump’s comments about the nuclear arsenal, even as they have weighed in via Twitter to echo Trump’s call for a U.S. veto of a United Nations Security Council resolution that was adopted Friday afternoon condemning Israeli settlements and ongoing construction in Palestinian territory.

But a spokeswoman for GOP Rep. Kevin Cramer, an early Trump supporter, said the North Dakota congressman discussed modernizing the nation’s nuclear arsenal during a visit earlier this month with the president-elect at Trump Tower. There, the Republican lawmaker shared a paper he’d written suggesting the new administration kick start in early 2017 a domestic nuclear enrichment facility that under current planning isn’t expected to break ground for eight more years.

“Such a commitment would re-establish America as the world leader in uranium enrichment technology, fully support U.S. nonproliferation initiatives, save multiple billions in appropriated funding over the life of the program, lessen dependence on foreign enrichers and create thousands of high-paying, high-quality construction, manufacturing and nuclear operating jobs in the near and intermediate term,” Cramer wrote.

Retiring Wisconsin GOP Rep. Reid Ribble told POLITICO that Trump would likely be out of step with a bipartisan core of lawmakers when it comes to expanding the U.S. nuclear arsenal.

“The general consensus among my colleagues in Congress is that the world is safer with fewer nuclear weapons than more,” he said. “I’m not sure what in the world he was thinking with that tweet. But I often think that way about his tweets.”

A frequent Trump critic, Ribble said he was “concerned” by the potential escalation implications from the president-elect’s remarks, though he also predicted they’d get more tempered in the weeks and months after Inauguration Day.

“Once his secretary of State is confirmed and things start to settle in and he’s taking more of his foreign policy briefings from State Department experts and given more of the global history and relationships, it’ll become a bit more sobering for him,” Ribble said.