President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE returns to Washington on Friday afternoon following a four-day trip to Europe that began with a state visit to the United Kingdom and culminated with a ceremony in France to mark the 75th anniversary of D-Day.

The state visit was a family affair for the president, who was accompanied by all of his adult children, and he stirred controversy with his comments about the royal family and British politics.

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Trump ended the trip on a somber note, delivering a speech at Normandy in front of dozens of veterans who participated in the June 1944 Allied invasion.

Here are six notable moments surrounding the president's travels.

Trump marks 75th anniversary of D-Day with world leaders

The state visit to the U.K. was largely scheduled around planned D-Day ceremonies, and Trump joined other world and U.S. officials at two separate events to commemorate the Allied invasion.

The president joined Queen Elizabeth II, British Prime Minister Theresa May Theresa Mary MayAre US-Japan relations on the rocks? Trump insulted UK's May, called Germany's Merkel 'stupid' in calls: report Bolton says Boris Johnson is 'playing Trump like a fiddle' MORE, Canadian Prime Minister Justin Trudeau Justin Pierre James TrudeauCanada says former ambassador to US violated conflict-of-interest law No new Canadian COVID-19 deaths reported for first time since mid-March Trudeau announces millions for first 'Black Entrepreneurship Program' MORE, French President Emmanuel Macron Emmanuel Jean-Michel MacronNavalny released from hospital after suspected poisoning US-China tensions shadow United Nations meeting The US is missing an opportunity in Lebanon MORE and German Chancellor Angela Merkel at an event in Portsmouth, England.

During a ceremony in Normandy on Thursday, Trump delivered a heartfelt tribute to the troops who stormed the beaches in France, with about 60 of those veterans in attendance.

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"You are the pride of our nation. You are the glory of our republic, and we thank you from the bottom of our hearts," Trump said.

While Trump has been critical of longtime U.S. allies like Germany and has chastised NATO members for inadequate defense spending, he embraced the legacy of cooperation left by D-Day.

The speech earned plaudits from some of his regular critics, with MSNBC host Joe Scarborough Charles (Joe) Joseph ScarboroughScarborough calls on Cuomo to walk back statement he made about Trump: 'Out of bounds' Mika Brzezinski: 'Super grossed out' by Trump speech attendees 'who put their lives at risk' Democrats tear into Trump's 'deep state' tweet: His 'lies and recklessness' have 'killed people' MORE among those praising its tone and message.

The president injects himself into British politics

The president's U.K. visit came while the country is in the midst of what Trump described Thursday as a "very interesting situation."

May is stepping down Friday after repeated failures to pass a Brexit deal through Parliament, setting off a leadership race while the country attempts to negotiate its way out of the European Union.

Trump weighed in on both topics and laid out the prospects of a bilateral trade deal between the U.S. and the U.K.

"I would think that it will happen and it probably should happen," Trump said of Brexit during a press conference with May. "This is a great, great country and it wants its own identity."

At the same press conference, he offered praise for Conservative Party politician Boris Johnson and British Foreign Secretary Jeremy Hunt, both prospective successors to May. Trump spoke with Johnson over the phone and met in person with Brexit Party leader Nigel Farage.

On trade, Trump predicted the two sides would establish a "great and very comprehensive" deal. He initially said Britain's publicly funded health system should be up for discussion as part of negotiations, but later reversed course amid backlash from British lawmakers.

Trump talks climate change with Prince Charles

The president met with Prince Charles during his visit, and the prince used that time to raise an issue he's passionate about: climate change.

Trump told Piers Morgan on "Good Morning Britain" that the two men discussed the matter. The president indicated that while he was moved by Charles's vigor, his views on the topic were relatively unchanged.

"I'll tell you what moved me is his passion for future generations," Trump said. "He's really not doing this for him. He's doing this for future generations."

When asked if he believes in climate change, Trump responded by citing shifting weather patterns.

"I believe that there's a change in weather and I think it changes both ways," he said. "Don't forget it used to be called global warming, that wasn't working. Then it was called climate change. Now it's actually called extreme weather because with extreme weather you can't miss."

Scientists have noted there is a difference between climate and the day-to-day weather.

Trump has long cast doubt on climate change. He has suggested it's a hoax invented by the Chinese and has pointed to winter storms when pushing back on global warming.

Trump doubles down on tariff threat against Mexico

Trump made waves just days before leaving for England when he threatened to impose a 5 percent tariff on Mexican imports unless the country stops all illegal migration into the United States.

While the president was out of town for negotiations in Washington, he tweeted about it on Monday, Tuesday and Wednesday, and on Thursday reiterated his willingness to follow through on the threat.

"We'll see what happens. But something pretty dramatic could happen," Trump said. "We've told Mexico the tariffs go on. And I mean it, too. And I'm very happy with it. And lot of people, senators included, they have no idea what they're talking about when it comes to tariffs. They have no — absolutely no idea."

Trump's tariff threat, which would go into effect on Monday if no deal is reached, has been met with pushback from some GOP senators who have warned the move could be detrimental to the U.S. economy.

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Trump stoked controversy before he even arrived in London by telling a British tabloid he didn't know Duchess of Sussex Meghan Markle was "nasty," a reference to her criticisms of him during the 2016 presidential race.

The president, irked by media coverage of his remark, claimed several times that he did not call Markle "nasty."

"I made no bad comment," Trump told reporters when asked if he wanted to apologize as he departed the White House.

Markle, who is married to Prince Harry, was absent from Trump's meetings with the royal family since she is on maternity leave. But Trump was asked about the incident during an interview with Morgan on "Good Morning Britain," and he took the opportunity to rehash the issue.

"I said, 'Well, I didn't know she was nasty,'" Trump said. "I wasn't referring to her, 'She's nasty.' I said she was nasty about me, and essentially I didn't know she was nasty about me."

"But you know what, she's doing a good job. I hope she enjoys her life," he added.

Trump's family travels with him

All of the president's adult children joined in on the trip to the U.K. — Donald Trump Jr. Don John Trump'Tiger King' star Joe Exotic requests pardon from Trump: 'Be my hero please' Zaid Jilani discusses Trump's move to cancel racial sensitivity training at federal agencies Trump International Hotel in Vancouver closes permanently MORE, Eric Trump Eric Frederick TrumpJudge orders Eric Trump to comply with New York AG's subpoena before Election Day Eric Trump uses misleading clip to blast Biden for using teleprompter Melania Trump: Ginsburg's 'spirit will live on in all she has inspired' MORE, Ivanka Trump Ivana (Ivanka) Marie TrumpSpecial counsel investigating DeVos for potential Hatch Act violation: report Trump, Biden vie for Minnesota Trump luxury properties have charged US government .1M since inauguration: report MORE and Tiffany Trump — as well as daughter-in-law Lara Trump Lara Lea TrumpHillicon Valley: Democrats demand answers over Russian interference bulletin | Google Cloud wins defense contract for cancer research | Cyberattack disrupts virtual classes Lara Trump campaigns with far-right activist candidate Laura Loomer in Florida Sunday shows - Democrats target Trump as violence flares MORE and son-in-law Jared Kushner Jared Corey KushnerAbraham Accords: New hope for peace in Middle East Tenants in Kushner building file lawsuit alleging dangerous living conditions Trump hosts Israel, UAE, Bahrain for historic signing MORE.

The Trumps appeared to revel in the pageantry of the visit, with Trump Jr., Eric Trump and Ivanka Trump sharing photos on Twitter from events at Winfield House and Buckingham Palace with members of the royal family and of events in Normandy.

Eric Trump and Trump Jr. also turned up at a few Irish pubs during the second leg of the trip, when the president stayed at a family property in Doonbeg.

"Ireland, thank you for the incredible support! We love you!" Eric Trump tweeted, along with photos of him and his older brother standing behind a bar.

A White House official said the president's children who are not in the administration paid their own way to join in the state visit.