NATO's top military commander warned Monday that what he called the "lethal alliance" would destroy "anything and everything" supporting an attack on allied territory and "break" enemy warfighting systems to thwart any potential future Russian assault.

"Should the adversary choose to press the attack or commit his reserves, we will break the warfighting system engaged against us," U.S. Air Force Gen. Alexus Grynkewich said at the hybrid warfare involving sabotage, arson and cyberattacks, alongside increasingly provocative military activity near NATO territory.

In 2025, multiple Russian drones entered Polish airspace during a large-scale attack on Ukraine, prompting a response from Polish and allied aircraft.

NATO launched Operation Eastern Sentry to strengthen defenses along its eastern flank.

Romania has also reported Russian drone incursions, while Estonia has accused Russian military aircraft of violating its airspace.

Grynkewich's remarks had followed a tense weekend between Russia and Ukraine, with Moscow launching fresh strikes against Ukrainian energy infrastructure despite diplomatic efforts to reduce hostilities.

President Donald Trump had announced that he had reached an agreement with Russian President Vladimir Putin to increase Russian diesel supplies to the U.S. and global markets.

The reported agreement included a waiver of certain U.S. sanctions on Russian energy exports.

Zelenskyy went on to accuse Russia of continuing attacks on Ukrainian energy facilities, casting doubt on prospects for a broader ceasefire.

The tensions have also been accompanied by recent nuclear warnings from Moscow.

On Sept. 30, Russia warned NATO that it could use nuclear weapons if the alliance attempted to isolate Kaliningrad, its heavily militarized Baltic Sea exclave between Poland and Lithuania.

In a diplomatic note obtained by increase defense spending and has questioned whether countries that fail to meet their obligations should expect U.S. protection.

Grynkewich sought to downplay concerns about Washington's commitment, recalling Trump's positive remarks about the alliance during the 2025 NATO summit in The Hague, Netherlands.

"I was in the room and I felt the love," Grynkewich said of the 2025 event.

"What I want to do is assure the one billion citizens of our alliance that we've got this. We know what we need to do. We know how we would do it," he added.

He also indicated a willingness to discuss suspected hybrid attacks more openly if individual NATO governments wanted him to address their concerns.

"If a nation wants me to, I'm happy to talk about it," he said.

The Warsaw Security Forum brought together European political and defense leaders as the continent grappled with Russia's continuing war in Ukraine and the growing threat of confrontation along NATO's eastern flank.