NATO Secretary-General Mark Rutte, during a visit to Warsaw, cautioned Russia on Wednesday that any aggression against Poland or any other NATO member would be met with a “devastating” response from the alliance.

Rutte’s remarks were made alongside Polish Prime Minister Donald Tusk, who stressed the importance of preparing for all possible outcomes of talks between Russia and the United States aimed at resolving the ongoing three-year conflict.

Nations along NATO’s eastern border, particularly Poland and the Baltic states, are concerned that these discussions might result in a settlement favorable to Russia. They fear such a result could enable Russian President Vladimir Putin to strengthen his military and pose a threat to other nations in the region in the future.

Rutte emphasized that Putin, nor anyone else, should believe they could act with impunity.

“If anyone were to miscalculate and think they can get away with an attack on Poland or on any other ally, they will be met with the full force of this fierce alliance. Our reaction will be devastating. This has to be very clear to Putin and anyone else who wants to attack us,” Rutte stated.

Rutte’s warning is delivered at a time when Trump’s return to power has challenged long-held security assumptions, prompting Europe to reduce its dependence on the U.S. for security and leading to significant new investments in weaponry by European nations.

Trump stated during a recent meeting with Rutte at the White House that he does not anticipate a peace agreement for Ukraine leading to Russian attacks on other countries.

Rutte has previously cautioned that Russia could potentially launch another attack on European soil before the end of the decade.

“Let’s not forget that Russia is and is remaining the most significant and dark threat to our alliance. Let’s not forget that Russia is moving into a wartime economy, and that will have a huge impact on their capacity and capability to build their armed forces,” Rutte said Wednesday.