NATO Secretary General Mark Rutte warned on Wednesday that any attack on Poland or another alliance member would meet a forceful response, reaffirming the bloc’s commitment to defending its eastern flank.

“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,” Rutte said.

“Our reaction will be devastating.”

Referring directly to Russian President Vladimir Putin, Rutte added: “This has to be very clear to Vladimir Vladimirovich Putin, and anyone else who wants to attack us.”

Rutte’s remarks, made alongside Polish Prime Minister Donald Tusk in Warsaw, comes amid growing concerns in Poland and the Baltic states that Russia could seek to test NATO’s unity if it prevails in Ukraine, perhaps through a limited military incursion or hybrid warfare.

Poland, which allocates 5% of its GDP to defence, is one of the alliance’s most heavily armed eastern members.

Tusk echoed Rutte’s stance, calling for a “just peace” in Ukraine.

“Only a just peace will give us all a sense of security,” he said.