David Jackson

USA TODAY

BRUSSELS – President Trump did not explicitly endorse the North Atlantic Treaty Organization's commitment to collective defense in his remarks at the military alliance's headquarters, even as he called on other leaders to spend more money on security.

Trump has never formally endorsed the NATO treaty's Article 5 commitment that an attack on one member country will be treated as an attack on all, making his silence on the subject in an address Thursday especially striking. The president who has touted an "America First" foreign policy did, however, refer more generally to "the commitments that bind us together as one" and promised to "never forsake the friends who stood by our side."

Trump refusal to explicitly endorse Article 5 raised some eyebrows. Ivo Daalder, the NATO ambassador under President Barack Obama, tweeted: "Deeply disappointing that Trump failed to reaffirm U.S. commitment to collective defense. Major missed opportunity."

Trump's first joint meetings with NATO leaders are largely ceremonial in nature. They include a working dinner and dedication ceremonies at the new NATO headquarters building, including memorials to the fall of Berlin Wall and to Article 5 of the NATO charter.

After Trump’s speech, White House spokesman Sean Spicer said it should have been assumed that Trump backed Article 5, given the fact he was speaking at the dedication of a memorial to it. “We’re not playing cutesy with this. He’s fully committed,” Spicer told reporters. “There’s 100 percent commitment to Article 5. I am somewhat perplexed when you’re at a ceremony that is centered around Article 5 people [that] could expect to hear certain words.”

And ahead of Trump's remarks, Secretary of State Rex Tillerson said that "of course we support Article 5," and noted that the only time NATO has invoked it was after the terrorist attacks on the United States on Sept. 11, 2001.

The new Article 5 memorial at the new NATO headquarters building is a piece of the wreckage from the destroyed World Trade Center. Praising the new building, Trump said, "I never asked once what the new NATO headquarters cost. I refuse to do that. But it is beautiful."

As Trump encouraged members to "contribute their fair share and meet their financial obligations" to NATO, he urged the military alliance to focus more on stopping terrorism to remain relevant in the 21st century.

"All people who cherish life must unite in finding, exposing and removing these killers and extremists – and yes, losers; they are losers," Trump said at the NATO event, condemning Monday's bombings at a concert in Manchester, England. The Islamic State has claimed responsibility for the attack.

For its part, NATO announced it would join a global coalition to battle the Islamic State, though not in any combat role.

Before NATO's announcement, all 28 members of the alliance were already members of the coalition battling the group known as ISIS. Some countries had opposed NATO inclusion, concerned that it might be drawn into a ground war in the Middle East.

Instead of combat, NATO Secretary General Jens Stoltenberg said the organization's involvement would include the use of surveillance planes, intelligence information sharing, and stepped-up military training in Iraq. In endorsing the plan, Stoltenberg cited the attack in Manchester.

“I expect NATO allies to step up and agree to do more in the fight against terrorism, not least because of the attack we saw in Manchester,” Stoltenberg told reporters.

While he has been criticized for being too close to Russian President Vladimir Putin, Trump at NATO also specifically called out Russia's military activity in Ukraine, saying that the "the NATO of the future must include a great focus on terrorism and immigration, as well as threats from Russia and on NATO's eastern and southern borders."

This appears to be Trump's most public callout of any Russian behavior, especially notable since the American president's first foreign trip came a week after the Justice Department appointed a special counsel to look into possible ties between Trump campaign associates and Russians who sought to influence the 2016 presidential campaign.

The U.S. intelligence community has accused Moscow of orchestrating a high-level campaign of cyberattacks and fake news to undermine the democratic process and Hillary Clinton's campaign, though Trump has since openly sought a warmer relationship with Moscow. That was highlighted in a controversial Oval Office meeting this month in which Trump reportedly disclosed highly classified information to Russian diplomats in an apparent attempt to get Moscow to step up its fight against the Islamic State.

In his NATO talks, Trump stressed that the United States is one of only five members in the 28-nation alliance that his hit the target of spending 2% or more of gross domestic product on military defense.

"I have been very, very direct with Secretary Stoltenberg and members of the Alliance in saying that NATO members must finally contribute their fair share and meet their financial obligations, for 23 of the 28 member nations are still not paying what they should be paying and what they’re supposed to be paying for their defense," Trump said.

Taking a somewhat hectoring tone at times, Trump said, "this is not fair to the people and taxpayers of the United States."

"And many of these nations owe massive amounts of money from past years and not paying in those past years," he continued. "Over the last eight years, the United States spent more on defense than all other NATO countries combined. If all NATO members had spent just 2 percent of their GDP on defense last year, we would have had another $119 billion for our collective defense and for the financing of additional NATO reserves."

Stoltenberg said member nations have made progress on the spending pledges.

European leaders greeted Trump's visit with some anxiety, noting that Trump has described NATO as "obsolete" in a world facing terrorist threats from non-state actors. Trump retracted his campaign trail claim the alliance was "obsolete" after an April meeting at the White House with Stoltenberg.

NATO and European Union members have also questioned Trump's positive comments about Putin, a foe of the NATO military alliance who has backed many anti-EU candidates in elections throughout the continent. Trump also unnerved European Union leaders by supporting last year's "Brexit" vote in which the United Kingdom opted to exit the EU.

On another diplomatic front, Trump fielded a complaint from British Prime Minister Theresa May about news leaks from U.S. officials on the British investigation of the Manchester terrorist attack. May told reporters she would make it clear to Trump "that intelligence that's shared between law enforcement agencies must remain secure."

In response, Trump issued a statement saying he has asked the Justice Department to investigate the leaks and prosecute people if necessary. "These leaks have been going on for a long time and my administration will get to the bottom of this," Trump said, adding that "there is no relationship we cherish more than the special relationship between the United States and the United Kingdom."

In addition to NATO, Trump held meetings Thursday with European Union leaders and the new president of France, Emmanuel Macron.

Even though Trump had kind things to say about Macron's election opponent, the anti-EU Marine Le Pen, during the campaign, the U.S. and French presidents appeared cordial and touted the long-standing alliance between their two countries.

“It is my great honor to be with the newly elected president of France, who ran an incredible campaign and had a tremendous victory," Trump said. "All over the world they’re talking about it. And we have a lot to discuss, including terrorism and other things."

He told Macron, "Congratulations. Great job.”

Responding in French, Macron said he was "very happy to be with President Trump," and "we have an extremely large agenda to discuss: the fight against terrorism, the economy, climate and energy."

In an ambitious first foreign trip as president, Trump traveled to Brussels after a series of meetings in Saudi Arabia and Israel about the Middle East peace process. Trump wraps up the trip at the weekend G-7 summit in Italy, where topics are expected to include counterterrorism, free trade, and climate change.

As Trump met with NATO and EU leaders, his predecessor Barack Obama spoke during his own visit to Europe and appeared to take issue with the current president's "America First" foreign policy.

In an apparent reference to Trump's proposed anti-migration wall between the United States and Mexico, Obama said: "In this new world we live in, we can’t isolate ourselves, we can’t hide behind a wall."