BRUSSELS -- President Donald Trump renewed his criticism of European allies Tuesday and said he was most optimistic about meeting with President Vladimir Putin of Russia as he departed for a summit in Brussels that threatens to highlight acrimony within NATO.
Trump's comments touched off a round of trans-Atlantic sniping with Donald Tusk, president of the European Council.
"The U.S. is spending many times more than any other country in order to protect them," Trump said on Twitter of the other members of the Atlantic alliance, hours before Air Force One left for Belgium. "Not fair to the U.S. taxpayer."
He complained anew about trade deficits with the European Union and seemed to threaten to cut U.S. military spending in a bid to compel other NATO members to increase theirs.
"NATO countries must pay MORE, the United States must pay LESS," Trump said in a separate tweet. "Very Unfair!"
Trump's remarks exacerbated concerns that he may torpedo the meeting that begins today, and with it the alliance's efforts to show unity and solidarity in the face of global threats, including from Russia.
"Frankly, Putin may be the easiest of them all -- who would think?" Trump said of his discussions over the next week, which include the NATO gathering and his first summit with the Russian president Monday in Helsinki.
Trump, who landed in Belgium during the middle of the soccer-mad nation's World Cup semifinals match, will head to London in between, where Prime Minister Theresa May's government is in turmoil over her plans for exiting the European Union.
Foreign Secretary Boris Johnson and exit Secretary David Davis resigned within hours of each other in protest of her plan. Trump said he might meet with Johnson in the U.K. despite his resignation.
Trump said Tuesday 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.
"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.
Trump's tweets prompted a tart retort from Tusk, who answered on Twitter saying that Europe was a friend worth protecting, unlike other countries with which Trump has cultivated relationships.
"Dear @realDonaldTrump," Tusk wrote. "US doesn't have and won't have a better ally than EU. We spend on defense much more than Russia and as much as China. I hope you have no doubt this is an investment in our security, which cannot be said with confidence about Russian & Chinese spending."
In comments after the signing of a joint EU-NATO declaration, Tusk said he wanted to address Trump's near-daily criticism of Europe and complaints that countries are "living off the U.S."
"Appreciate your allies," Tusk said. "After all, you don't have that many."
Tusk, the president of the body that represents leaders of EU member states, many of which are also in NATO, has a history of publicly challenging Trump at a time when many foreign leaders are reluctant to criticize him openly.
Last month, he said that Trump's politics had put trans-Atlantic relations "under tremendous pressure" and warned Europeans to prepare for darker times. In May, he tweeted that Trump's decisions could prompt the question, "With friends like that, who needs enemies."
On Tuesday, as he left the White House for the short helicopter ride to Andrews Air Force Base to begin his trip to Europe, Trump seemed unmoved by Tusk's latest pushback.
"Well, we do have a lot of allies, but we cannot be taken advantage of," the president said, when asked about Tusk's comments. "We're being taken advantage of by the European Union."
Trump told reporters 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 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.
Information for this article was contributed by Julie Hirschfeld Davis of The New York Times; and by Jill Colvin, Jonathan Lemire and Zeke Miller of The Associated Press.
A Section on 07/11/2018