Here's a look at the key issues where the United States has shifted gears, including tariffs, support for Ukraine and urging Europe to take greater control of its own defense.

- 'Pathetic' freeloaders -

A stunning security breach that saw a journalist inadvertently added to a chat group of top Trump officials discussing plans to attack Huthi rebels in Yemen revealed highly critical comments about European allies.

In the chat, a user identified as US Vice President JD Vance expressed doubts about conducting military strikes on the rebels, arguing that Europe was more impacted than the US by the group's attacks on Red Sea shipping.

"I just hate bailing Europe out again," Vance wrote in the group.

A user identified as Defense Secretary Pete Hegseth replies: "I fully share your loathing of European freeloading. It's PATHETIC."

Trump echoed Hegseth's comments Tuesday.

"Yeah, I think they've been freeloading," he told reporters. "The European Union's been absolutely terrible to us on trade."

- Hostile speech -

Vance also shocked Europe when he used a February speech at a security forum in Munich to attack EU policies on immigration and free speech.

The vice president charged that "across Europe, free speech, I fear, is in retreat," and that censorship was a bigger threat than Russian or Chinese military aggression.

"No voter on this continent went to the ballot box to open the floodgates to millions of unvetted immigrants," he added, defending populist right-wing parties.

- 'Screw' the US -

Trump said last month that the EU was formed to "screw" the United States, laying bare his hostility to the longtime US partner as he detailed new tariffs.

"But now I'm president," he said.

Trump's 25-percent tariffs on steel and aluminum imports took effect on March 12. EU countermeasures are set to begin in April.

- 'Have to have' Greenland -

Trump has insisted he wants the United States to take over Greenland, a Danish territory, for national security purposes and has refused to rule out the use of force to achieve this.

"We need Greenland for international safety and security. We need it. We have to have it," Trump told podcaster Vince Coglianese Wednesday. "I hate to put it that way, but we're going to have to have it."

The vast territory is located strategically in the Arctic and is rich in mineral resources.

Vance has insisted the president is not afraid of ruffling feathers on the issue, citing national security.

"He doesn't care about what the Europeans scream at us," Vance told Fox News last month.

- Shifting power with Putin -

Perhaps the most shocking shift has been on Russia and Ukraine -- best epitomized by a meeting between Trump and Ukrainian leader Volodymr Zelensky at the White House on February 28 in which the US President and Vice President JD Vance berated their wartime ally in front of the world's media.

Trump has appeared to lean towards Russian President Vladimir Putin, undermining Zelensky's legitimacy and suggesting that Ukraine was responsible for the Russian invasion, rather than Moscow.

In February he blindsided Kyiv and European allies by agreeing to launch peace talks after a phone call with Putin.

European powers insisted that they and Kyiv must have a seat at the table of any future negotiations -- but days later, top US officials met Russian negotiators in Saudi Arabia to lay the ground for talks.

Europe was not represented, nor was it in the latest round of Saudi discussions Sunday and Monday.

And in a seismic shift at the United Nations, Washington sided with Moscow in two votes last month, avoiding condemnation of Putin's war in Ukraine.

When Britain and France said they would be willing to deploy ground troops in Ukraine, Vance responded by mocking the prospect of sending "20,000 troops from some random country that has not fought a war in 30 or 40 years."