"A strong US, a strong European Union and a strong NATO, not weaker," is important to "common European-American interests," Tusk said on the X social media network.

"Think about it, Mr President and dear American friends, before you decide to impose tariffs against your closest allies. Cooperation is always better than confrontation," he said.

At the same time, Tusk's government announced that it had signed a $2 billion deal with the United States for logistical support for its US-designed Patriot air defence systems.

The social-media messaging and the defence contract announcement came before Trump is due on Wednesday to unveil his tariffs.

The move, against multiple countries, including those in the European Union, is likely to intensify a trade war which analysts said could damage economies in America, Europe and elsewhere.

European leaders are also concerned about Trump's rapprochement with Moscow and doubts about the US commitment to NATO.

Tusk, in a video posted on X, said that, "for us, Poles, our friendship, our alliance, our mutual loyalty is not an abstraction. We spend almost 5% of our GDP on defence."

Polish Defence Minister Wladyslaw Kosiniak-Kamysz backed that up by saying that the air defence deal was an "investment of around $2 billion".

"This is equipment delivery, logistical support for well-functioning Patriot batteries, for the whole system," he added at the signing ceremony in the central town of Sochaczew.

The Central European country has ramped up its military spending since Russia invaded Polish ally Ukraine in 2022. Poland shares a border with both nations.

Trump has demanded that NATO members increase defence spending.

Poland plans to spend 4.7 percent of its annual economic output on defence in 2025.

"America could and always can count on Poland. You have only friends here. And I can say the same thing about Europe as a whole," Tusk said.

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