French President Emmanuel Macron, left, hugs President-elect Donald Trump as he arrives at the Elysee Palace, Saturday, Dec. 7, 2024 in Paris. (AP Photo/Aurelien Morissard)

NEW YORK (AP) -- He's making threats, traveling abroad and negotiating with world leaders.

Donald Trump has more than a month and a half to go before he's sworn in for a second term. But the Republican president-elect is already moving aggressively not just to fill his Cabinet and outline policy goals, but to achieve them.

Trump has threatened to impose a 25% tariff on goods from Canada and Mexico, prompting emergency calls and a visit from Canada's prime minister that resulted in what Trump claimed were commitments from both U.S. allies on new border security measures.

The incoming president has warned there will be "ALL HELL TO PAY" if Hamas does not release the hostages being held in Gaza before his inauguration on Jan. 20, 2025.

And this weekend, Trump returned to the global stage, joining a host of other foreign leaders for the reopening of the Notre Dame Cathedral five years after it was ravaged by a fire. There, he was welcomed like a sitting dignitary, with a prime seat next to French President Emmanuel Macron.

Absent in Paris: lame duck President Joe Biden, who has largely disappeared from headlines, except when he issued a pardon of his son, Hunter, who was facing sentencing for gun crimes and tax evasion. First lady Jill Biden attended in his place.

"I think you have seen more happen in the last two weeks than you've seen in the last four years. And we're not even there yet," Trump said in an over-the-top boast at an awards ceremony Thursday night.

For all of Trump's bold talk, though, it is unclear how many of his efforts will bear fruit.

Breaking precedent

The pre-inauguration threats and deal-making are highly unusual, like so much of what Trump does, said Julian Zelizer, a political historian at Princeton University.

"Transitions are always a little complicated in this way. Even though we talk about one president at a time," he said, "the reality is one president plus. And that plus can act assertively sometimes."

Zelizer said that is particularly true of Trump, who was president previously and already has relationships with many foreign leaders such as Macron, who invited both Trump and Biden to Paris this weekend as part of the Notre Dame celebration.

"Right now he's sort of governing even though he's not the president yet. He's having these public meetings with foreign leaders, which aren't simply introductions. He's staking out policy and negotiating things from drug trafficking to tariffs," Zelizer said.

Foreign leader meetings

Trump had already met with several foreign leaders before this weekend's trip. He hosted Argentinian President Javier Milei in Florida at his Mar-a-Lago club in November. After the tariff threat, Canadian Prime Minister Justin Trudeau made a pilgrimage to Mar-a-Lago for a three-hour dinner meeting. Canadian officials later said the country is ready to make new investments in border security, with plans for more helicopters, drones and law enforcement officers.

Incoming Trump aides have also been meeting with their future foreign counterparts.

On Wednesday, several members of Trump's team, including incoming national security adviser Mike Waltz, met with Andriy Yermak, a top aide to Zelenskyy, in Washington, as Ukraine tries to win support for its ongoing efforts to defend itself from Russian invasion, according to a person familiar with the meeting. Yermak also met with Trump officials in Florida, he wrote on X.

That comes after Trump's incoming Middle East envoy, Steve Witkoff, traveled to Qatar and Israel for high-level talks about a cease-fire and hostage deal in Gaza, according to a U.S. official familiar with the efforts, meeting with the prime ministers of both countries. The official was not authorized to publicly discuss the matter and spoke on condition of anonymity.

One president, two voices

There is no prohibition on incoming officials or nominees meeting with foreign officials, and it is common and fine for them to do so -- unless those meetings are designed to subvert or otherwise impact current U.S. policy.

Trump aides were said to be especially cognizant of potential conflicts given their experience in 2016, when interactions between Trump allies and Russian officials came under scrutiny. That included a phone call in which Trump's incoming national security adviser, Michael Flynn, discussed new sanctions with Russia's ambassador to the United States, suggesting things would improve after Trump became president. Flynn was later charged with lying to the FBI about the conversation.

Trump's incoming press secretary Karoline Leavitt said that "all transition officials have followed applicable laws in their interactions with foreign nationals."

She added: "World leaders recognize that President Trump is returning to power and will lead with strength to put the best interests of the United States of America first again. That is why many foreign leaders and officials have reached out to correspond with President Trump and his incoming team."

Such efforts can nonetheless cause complications.

If, say, Biden is having productive conversations on a thorny foreign policy issue and Trump weighs in, that could make it harder for Biden "because people are hearing two different voices" that may be in conflict, Zelizer said.

Leaders like Russia's Vladimir Putin and Netanyahu may also anticipate a more favorable incoming administration and wait Biden out, hoping for a better deal.

Coordination between incoming and outgoing administrations

Although there is no requirement that an incoming administration coordinate calls and meetings with foreign officials with the State Department or National Security Council, that has long been considered standard practice.

That is, in part, because transition teams, particularly in their early days and weeks, do not always have the latest information about the state of relations with foreign nations and may not have the resources, including interpretation and logistical ability, to handle such meetings efficiently.

It is unclear the level of State Department involvement, but the Biden and Trump teams say they have been talking, particularly on the Middle East, with the incoming and outgoing administrations having agreed to work together on efforts to free hostages who remain held in Gaza, according to a U.S. official, who was not authorized to comment publicly about the sensitive talks and spoke on condition of anonymity.

That includes conversations between Witkoff and Biden's foreign policy team as well as Waltz and Biden's national security adviser Jake Sullivan.

Last month, Biden administration officials said they had kept Trump's team closely apprised of efforts to broker a ceasefire deal between Israel and Hezbollah on the Israel-Lebanon border.

"I just want to be clear to all of our adversaries, they can't play the incoming Trump administration off of the Biden administration. I'm regularly talking to the Biden people. And so, this is not a moment of opportunity or wedges for them," Waltz said Friday in a Fox Business interview.

Sullivan echoed those comments at the Ronald Reagan National Defense Forum Saturday.

"It has been professional. It has been substantive. And frankly, it has been good," he said of their coordination on national security issues. "Obviously we don't see eye to eye on every issue, and that's no secret to anybody," he went on. But he said both teams believe "it is our job on behalf of the American people to make sure this is a smooth transition," particularly given the seriousness of issues like the war in Ukraine, conflicts in the Middle East and threats from China.

"The nature of the world we find ourselves in today only elevates our responsibility to be engaged, to talk regularly, to meet regularly, to be transparent, to share, and to make sure it's an effective transition," he said.

Taking credit already

Trump's team, meanwhile, is already claiming credit for everything from gains in the stock and cryptocurrency markets to a decision by Walmart to roll back diversity, equity and inclusion policies Trump opposes.

"Promises Kept -- And President Trump Hasn't Even Been Inaugurated Yet," read one press release that claimed, in part, that both Canada and Mexico have already pledged "immediate action" to help "stem the flow of illegal immigration, human trafficking, and deadly drugs entering the United States."

Mexican President Claudia Sheinbaum has stopped short of saying Trump mischaracterized their call in late November. But she said Friday that Trump "has his own way of communicating, like when we had the phone call and he wrote that we were going to close the border. That was never talked about in the phone call."

Earlier this week, Mexico carried out what it claimed was its largest seizure of fentanyl pills ever. Seizures over the summer had been as little as 50 grams per week, and after the Trump call, they seized more than a ton.

Biden, too, tried to take credit for the seizure in a statement Friday night.