President-elect Donald Trump’s running commentary on sensitive foreign policy issues before taking office is ruffling feathers, with critics complaining he’s violating a longstanding tradition of deference to the incumbent White House during transitions.

Since winning the election, Trump has said America’s “one-China” policy regarding China and Taiwan is up for negotiation, tweeted that the US should refuse to accept an underwater drone seized and returned by China, criticized the intelligence community’s findings on Russian hacking, and threatened to reverse ongoing overtures toward Cuba unless the Cuban government meets unspecified conditions.

Thursday morning, Trump called on President Obama to block a UN resolution on Israeli settlements before the White House had a chance to announce its position (the vote has since been delayed). Later in the day, Trump tweeted that the United States “must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes.”

Incoming leaders have typically abided by a “one president at a time” rule in order to avoid sending mixed messages and to give themselves time to consult intelligence and confer with their incoming cabinet and inherited civil service.

“It’s confusing,” Stephen Hess, a policy analyst at Brookings who has worked under presidents from both parties, said. “The president-elect doesn’t really have the power to do these things and, while suggesting them at this time, it may look very different to him after January 20.”

Related: Trump Stuns Nuclear Experts With Apparent Call to Expand Arsenal

Trump shattered a variety of norms during the campaign and often complained about an atmosphere of “political correctness” that he said had prevented politicians from speaking plainly about challenges facing the country. Critics are concerned that his often unpredictable style could create problems for both his incoming administration and the current one.

Congressman Jared Huffman (D-CA) told NBC News he was so alarmed by Trump’s behavior that he introduced the “One President at a Time Act” earlier this month, which would clarify that the Logan Act, which prohibits private citizens from conducting foreign policy, also applies to incoming presidents.

“In the past, president-elects have shown good judgement and restraint in understanding that our duly elected officials need to conduct foreign policy while they’re in office,” Huffman said. “We've never had a president-elect with such impulse control problems.”

Modern presidents have used nearly identical language to skirt questions on foreign affairs during their transition. President Bill Clinton told the press after his 1992 victory that he would “reaffirm the essential continuity of American foreign policy” and recognized “that America has only one president at a time.”

President George W. Bush declined questions on topics like North Korea and Israel until he took the oath of office in early 2001. “We have one president, and we'll have one president, and the current president is President Clinton, and our nation must speak with one voice,” Bush said at a press conference.

Obama took a similar stance after his election in 2008, telling reporters that “when it comes to foreign affairs, it is particularly important to emphasize that there is one president at a time” after declining a question on Israeli operations in Gaza. He notably repeated the phrase last month after Trump’s election, reminding the press that “there is one president at a time” before embarking to meet foreign leaders in Greece, Germany, and Peru.

“Only the President has the authority to conduct foreign policy on behalf of the United States, and there needs to be absolute clarity about his positions and the policies of the US,” Tommy Vietor, who served as Obama’s national security spokesman, said in an e-mail. “If there's ambiguity, an adversary can use it to gain leverage on us and it creates general confusion and uncertainty among our allies.”

Max Stier, CEO of the Partnership for Public Service, said that the transition process has varied over the years and that he believed the White House was still on track for a smooth hand-off between staff. He noted, for example, that Obama and Bush took a more active approach than was normal toward negotiating economic policy together in order to ensure stable leadership during the financial crisis.

“I do think there is a difference between addressing internal issues and presenting our views to the larger world,” he added.

Trump’s transition team did not immediately respond to a request for comment on their interpretation of the “one president at a time” tradition.