He was speaking after a briefing from NATO Secretary General Mark Rutte on the situation in the region and developments on the Ukrainian front.
"As I warned, escalation from Russia is continuing. Ukraine needs greater air support, which also matters for our own security. This is a task for all of Europe," Tusk said in a post published on X.
He added: "The next six months will be decisive, and we must be prepared, as Poland and as NATO, for various scenarios. We cannot rule out a provocation from Russia against one of NATO's members."
Separately, US news outlet Politico reported, citing two sources familiar with the matter, that CIA Director John Ratcliffe warned Russian officials against escalation and attacks on NATO states, particularly Lithuania, Latvia and Estonia, during an unannounced visit to Moscow on Tuesday.
The Institute for the Study of War said that the trip "suggests that Russia may be preparing to conduct an act of aggression against a NATO member in the relatively near term to invalidate NATO’s Article 5."
Ratcliffe travelled to Moscow on a military transport plane with a stopover in Riga.
It was the first publicly known visit by a CIA director to Moscow since 2021, when his predecessor Bill Burns met Russian President Vladimir Putin to warn against in of Ukraine.
(ał)
Source: PAP