Visiting a city he once called all sorts of names to meet with the leaders of one alliance he threatened to abandon and another whose weakening he cheered, President Donald Trump will address a continent Thursday still reeling from his election and anxious about his support.

Trump traveled Thursday morning to the European Union headquarters in Brussels for meetings with Donald Tusk, the president of the European Council, Jean-Claude Juncker, the president of the European Commission, and other EU officials.

Trump appeared to be greeted warmly by the leaders, despite his past comments publicly cheering the United Kingdom’s vote to leave the EU last summer and slamming the alliance during his transition as “a vehicle for Germany.” Trump has taken a less combative tone since taking office, praising the alliance as “wonderful” and saying a strong Europe is very important to him and the United States.

After meeting with Trump on Thursday at the EU, European Council president Donald Tusk said he and the U.S. precedent agreed on the need to combat terrorism but some differences loomed large.

“Some issues remain open, like climate and trade. And I am not 100 percent sure that we can say today — we means Mr. President and myself — that we have a common position, common opinions about Russia,” said Tusk, who said unity needed to be found around values like freedom and human rights and dignity.

“The greatest task today is the consolidation of the whole free world around those values,” he said.

Later in the day, Trump is slated to meet with France’s new president and attend his first meeting of NATO, the decades-long partnership that has become intrinsic to safeguarding the West but has been rattled by the new president’s wavering on honoring its bonds. Trump has mused about pulling out of the pact because he believed other countries were not paying their fair share and he has so far refused to commit to abiding by Article 5, in which member nations vow to come to each other’s defense.

A new strain emerged on the relationship between the U.S. and a key European ally: a British official said Thursday that police in Manchester will stop sharing information about their bombing investigation with the U.S. until they get a guarantee that there will be no more leaks to the news media.

British Prime Minister Theresa May said she plans to push Trump that “intelligence that is shared between our law enforcement agencies must remain secure.” The source of the leak is unclear. Trump did not respond to shouted questions as to whether the UK can trust the US with sensitive material.

But the European capitals that have been shaken by Trump’s doubts may soon find a degree of reassurance. Just like his position on the EU, the president has recently shifted gears, praising NATO’s necessity. Secretary of State Rex Tillerson said Wednesday that “of course” the United States supports Article 5, though Trump still wants other nations to meet their obligation to spend 2 percent of their gross domestic product on defense.

“I think you can expect the president to be very tough on them, saying, ‘Look the U.S. is spending 4 percent. We’re doing a lot,'” Tillerson told reporters on Air Force One. He also said he thought it would be “a very important step” for NATO to join the 68-nation international coalition fighting the Islamic State. The move, which is expected during Thursday’s meeting, is symbolically important, especially since the terror group claimed responsibility Tuesday for a deadly explosion at an Ariana Grande concert in Manchester, England.

An anti-terror coordinator may also be named. But most changes will be cosmetic, as NATO allies have no intention of going to war against IS.

The 28 member nations, plus soon-to-join Montenegro, will renew an old vow to move toward the 2 percent figure for defense by 2024. Only five members currently meet the target: Britain, Estonia, debt-laden Greece, Poland and the United States, which spends more on defense than all the other allies combined.

European leaders have been particularly unnerved by Trump’s reticence about NATO due to renewed aggression by Russia, which seized Crimea from the Ukraine in 2014 and, intelligence officials believe, interfered in last year’s American elections.

While in Belgium, Trump will unveil a memorial to the terrorist attacks of Sept. 11, 2001, the only time in the alliance’s history that the Article 5 mutual defense pledge has been invoked. He will also speak at NATO’s gleaming new $1.2 billion new headquarters.

But while the Europeans greeted Trump warily, tens of thousands gathered in Berlin to hear his predecessor and German Chancellor Angela Merkel discuss democracy and global responsibility at a Protestant conference as the country marks the 500th anniversary of the Reformation. Barack Obama made a case for American involvement internationally, saying “we can’t isolate ourselves, we can’t hide behind a wall” in the hours before Merkel was set to meet Trump in Brussels.

In total, Trump will spend about 24 hours in Brussels, a city where he said making a home would be “like living in a hellhole” because of Muslim immigration and terror threats.

Brussels is the fourth stop on Trump’s nine-day international trip, the first such trip of his presidency. Protests were slated to take place outside the heavily guarded security perimeter near the city’s airport and downtown. In the wake of this week’s Manchester bombing, Belgium remains on security Level 3 — meaning that the threat of an extremist attack “is possible and likely.” The country has been on that level of alert since suicide-bomb attacks on the Brussels airport and subway killed 32 people last year.

Trump is slated to leave Brussels late Thursday for the final piece of his trip, a two-day stay in Sicily for G-7 meetings.

(AP)