A senior European Union official lashed out Tuesday at President Donald Trump, lambasting the U.S. leader for his constant criticism of European allies and urging him to remember who is friends are when he meets Russian President Vladimir Putin next week.

European Council President Donald Tusk directed a message at Trump, saying “it is always worth knowing who is your strategic friend and who is your strategic problem.”

His blunt remarks came as he signed a joint EU-NATO declaration in Brussels with alliance Secretary-General Jens Stoltenberg.

NATO has been struggling to put on a display of unity for a two-day summit at its new headquarters, amid deep divisions among member countries over Trump’s policies on trade and his decision to withdraw from the Iran nuclear deal and global climate agreement.

“America does not have and will not have a better ally than Europe today. Europeans spend on defense many times more than Russia and as much as China and I think you can have no doubt, Mr. President, that this is an investment in common American and European defense and security which cannot be said with confidence about Russian or Chinese spending,” Tusk said.

Trump has routinely criticized his NATO allies for failing to spend enough on their defense budgets and he is likely to repeat his demands for more money in Brussels on Wednesday.

Tusk too urged the Europeans to increase spending as they have promised, but said: “Dear America, appreciate your allies, after all you don’t have all that many.”

The former Polish prime minister, who these days chairs summits of EU leaders and will take part in the NATO meeting, recalled that Europe also came to Washington’s help after the Sept. 11 attacks, and that 870 European troops have fought and died in Afghanistan, including 40 from Poland.

“Mr. President, please remember about this tomorrow when we meet at the NATO summit. But above all when you meet President Putin in Helsinki” on July 16.

(AP)