Following sustained criticism of Europe by President Donald Trump, the president of the European Council, Donald Tusk, fired back and warned Trump that he should appreciate his allies.

Tusk, a former Polish prime minister, said in a statement on the eve of the NATO summit in Brussels, “Dear America, appreciate your allies, after all you don’t have that many.” He added, “for a long time now” Trump has been criticising Europe almost daily for insufficient contributions to the common defence capabilities and for living off the U.S. Addressing the president directly, he said, “Dear President Trump: America does not have, and will not have, a better ally than Europe,” The Independent reported.

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Tusk also shared his sentiment about the U.S. on Twitter, saying the EU spends on defense more than Russia and as much as China.

On Tuesday, Trump travelled to Brussels for the NATO meeting, which is also being attended by leaders like Theresa May and Angela Merkel. Ahead of his visit, he tweeted :

Tusk has previously warned member states they should prepare for “worst-case scenarios” with Trump leading the United States regarding his threats to withdraw U.S. military protection. According to The Independent, EU officials say that Tusk privately believes Trump is “dangerous” and that his policy represents a new American doctrine without fixed friends or enemies.