NATO is readying a strategy on how to counter a potential Russian attack, with a top commander, Alexus Grynkewich, expected to elaborate on his "theory of victory" next week in Poland, a spokesperson said Monday, as fears grow over the threat from Moscow.

"The Supreme Allied Commander Europe's theory of victory is simple: maintain NATO's advantage, which is consistent with and grounded upon the alliance's deterrence and defense plans," Colonel Martin O'Donnell, a spokesperson for the U.S. general, said.

"But given the unsettled and complex global security environment, we need to set conditions now to deter aggression and, if necessary, win if attacked," O'Donnell said, noting the theory sets out a framework to do just that.

He said that Grynkewich would speak about his ideas at a security conference in Warsaw next Monday.

The move from the top military commander comes as NATO seeks to send a message to Moscow to halt what Western officials say is a "hybrid" campaign of sabotage and interference against Ukraine's backers.

Fears have grown in recent months that the Kremlin is stepping up its actions after high-profile incidents, including the discovery of an explosive-laden drone at a German airport.

NATO traditionally closely guards its defense plans to counter any attack by Russia.