Tusk: U.S. pledges military retaliation if Russian attacks Ukraine again

Tusk stressed that the guarantees are designed to make it clear to Moscow that a renewed Russian attack on Ukraine would trigger a military reaction from the United States.

Washington believes that its involvement will make robust security guarantees for Ukraine possible.

"The breakthrough is that, perhaps for the first time, it has become so clear that Ukraine, the Americans, and the Europeans are on the same wavelength," Tusk said.

"We need to apply even more pressure to demonstrate that we will not allow ourselves to be divided as the West. It is extremely important that we act together with the Americans and Ukrainians so the Russians can see this."

Tusk emphasized that Poland would not pressure Ukraine to make any concessions during negotiations.

"This must be a decision based on the Ukrainians' own calculations and assessments. Security guarantees for Ukraine are also, in a sense, security guarantees for Poland. If Ukraine were exposed to renewed aggression, it would pose a serious risk to Poland and other countries close to the front line.”

The Polish prime minister also called on Western partners to unite around the issue of a ceasefire.

"The only way to convince Russia to engage in meaningful negotiations to end the war, or at least agree to a ceasefire, is for the entire West to act together," Tusk said.

This echoes an earlier statement by German Chancellor Friedrich Merz that the United States is prepared to assume legally binding security guarantee obligations for Ukraine comparable to NATO’s Article 5.