BRUSSELS >> With Europe’s wary eyes upon him, President Donald Trump launched a weeklong trip there today with harsh criticism for NATO allies and predicted the “easiest” leg of his journey would be his scheduled sit-down with Russian President Vladimir Putin.

As he departed the White House for a four-nation European tour, Trump did little to reassure allies fretting over the risk of damage he could do to the 69-year-old trans-Atlantic mutual defense pact and his potential embrace of Putin during a summit in Helsinki.

Trump said today he “can’t say right now” if Putin is a friend or foe, but called him a “competitor.” The U.S. intelligence community has concluded that Russia interfered in the 2016 election to boost Trump’s candidacy, and warns of further attempts at interference both in the 2018 midterms and in European elections.

Trump arrived in Brussels on the eve of the NATO summit after repeated attacks on the pact. He told reporters in Washington before leaving that “Frankly it helps them a lot more than it helps us” and then later tweeted from Air Force One that he may demand reimbursements from the European member nations.

Trump has been pressing NATO countries to fulfill their goal of spending that 2 percent of their gross domestic products on defense by 2024. During his presidential campaign, he suggested he might only come to the defense of NATO nations that fulfilled their obligation. And a year ago, during his first visit to its Belgium headquarters, Trump initially declined to explicitly support the organization’s defense agreement.

Trump, who landed in Belgium during the middle of the soccer-mad nation’s World Cup semifinals match, will later head to London, where Prime Minister Theresa May’s government is in turmoil over her plans for exiting the European Union.

European Council President Donald Tusk said today in a message to Trump that “it is always worth knowing who is your strategic friend and who is your strategic problem.” Tusk recalled that the Europeans are spending more than Russia and as much as China on defense. NATO estimates that 15 members, or just over half, will meet the benchmark by 2024 based on current trends.

“Getting ready to leave for Europe. First meeting — NATO. The U.S. is spending many times more than any other country in order to protect them,” Trump tweeted this morning, adding: “Not fair to the U.S. taxpayer. On top of that we lose $151 Billion on Trade with the European Union. Charge us big Tariffs (& Barriers)!”

On Monday he’d tweeted the situation was “not fair, nor is it acceptable,” and insisted that NATO benefits Europe “far more than it does the U.S.”

He added: “NATO countries must pay MORE, the United States must pay LESS. Very Unfair!”

Trump, who has compared the sentiment that underpinned the Brexit vote to leave the EU to his own election, will be making his maiden presidential trip to Britain at a fraught time for May. Foreign Secretary Boris Johnson and Brexit Secretary David Davis resigned within hours of each other in protest of her plan. Trump said might meet with Johnson in the UK despite his resignation.

Trump’s visit is expected to attract large protests in London and elsewhere in Britain.

Trump’s weeklong trip to Europe will continue with a stop in Scotland before ending with a sit-down in Helsinki with Putin.

He said that of the high-stakes meetings of his trip, “Putin may be the easiest of them all.”

“I think that getting along with Russia, getting along with China, getting along with others is a good thing, not a bad thing,” he added.

The meeting will be closely watched to see whether Trump will rebuke or embrace Putin, who has repeatedly denied the allegations of election meddling, in spite of evidence to the contrary.