Trump faced protests on his arrival in Brussels but he is getting a red-carpet welcome from Western allies.
Trump faced protests on his arrival in Brussels but he is getting a red-carpet welcome from Western allies eager to persuade him that his earlier harsh criticisms of them were misplaced.
Despite Trump having backed Britain's Brexit vote last year, it was all smiles at the headquarters of the European Union as Trump met the bloc's top two officials, Donald Tusk and Jean-Claude Juncker.
"I'll aim to convince POTUS that euro-atlanticism means the free world co-operating to prevent (a) post-West world order," European Council chief Tusk, a former Polish premier, tweeted before the meeting.
Trump's focus is however on terrorism, with the deadly attack on a pop concert in Manchester, England this week adding to the urgency of his calls for NATO to step up the fight against the jihadis.
"When you see something like what happened a few days ago you realise how important it is to win this fight. And we will win this fight," said Trump Wednesday after meeting Belgian Prime Minister Charles Michel, whose own country suffered Islamic State suicide attacks in March 2016.
The NATO military alliance -- which Trump on the campaign trail dismissed as "obsolete" for focusing on Russia instead of terrorism -- is set to bow to his demands that it formally join the US-led coalition against IS.
"This will send a strong political message of NATO's commitment to the fight against terrorism," NATO Secretary General Jens Stoltenberg told reporters ahead of Trump's meeting with the alliance's other 27 leaders.
France, Germany and Italy dropped their objections so long as it was made clear that the alliance would have no combat role, with NATO only providing increased AWACS surveillance planes, support and training.
In return they are hoping for a public display of commitment from Trump to Article 5, the alliance's one-for-all collective defence pledge. Trump had suggested this could depend on when allies paid their dues.
Trump's entourage warned that the billionaire president would push allies heavily on meeting their commitment to spend 2.0 percent of GDP on defence, agreed in 2014.
"I think you can expect the president to be very tough on them," Secretary of State Rex Tillerson told reporters travelling with Trump.
But Trump is set to face pressure from British Prime Minister Theresa May over leaks to the US media of details of the probe into the Manchester attack.
British police said the leaks have "undermined" the investigation.
Brussels could be the toughest leg yet of what has so far been a largely trouble-free first foreign trip for Trump, who came direct from a meeting with Pope Francis at the Vatican, and previously visited Saudi Arabia, Israel and the Palestinian Territories.
On his arrival on Wednesday in Brussels, the city he once said had been turned into a "hellhole" by Muslim immigration, the president was greeted by around 9,000 protesters saying "Trump not welcome."
Further rallies were expected Thursday and security was tight across the city with helicopters flying overhead and key roads shut down.
Trump had alarmed the EU by not only calling on more countries to follow Britain out of the exit door but also by calling it a vehicle for German dominance of the continent.
Tusk and Juncker will tell the US president that since last year's shock Brexit vote, the EU is "in a completely different place" after populist anti-EU candidates lost in France and the Netherlands, a senior EU official said.
Trump will have a private lunch with new French President Emmanuel Macron, whose recent victory over far-right leader Marine Le Pen has been seen as a beacon of hope by Brussels, before heading to NATO.
The NATO summit will however be full of pomp and symbolism, with the keen-to-impress alliance showing off its new $1.2-billion (1.1 billion-euro) headquarters and staging a flypast.
At a ceremony with German Chancellor Angela Merkel, Trump will unveil a memorial to the September 11, 2001 attacks featuring part of the destroyed World Trade Center, while Merkel does the same for a fragment of the Berlin Wall.
9/11 was the only time that Article 5 has been triggered, a fact NATO leaders have repeatedly pointed out to Trump.
Trump's wife Melania, meanwhile, is set to visit a museum dedicated to the surrealist artist Rene Magritte and a leading leather store while in Brussels.
The high-profile trip has diverted attention from Trump's domestic pressures amid the probe into alleged Russian ties with his campaign.