Two Russian Su-27 jets carried out what the US military described as a reckless intercept of the MQ-9 “Reaper” drone in international airspace before one of them collided with it on Tuesday, causing the drone to crash into the sea.

Several times before the collision, the Russian fighter jets dumped fuel on the MQ-9, possibly trying to blind or damage it, and flew in front of the unmanned drone in unsafe manoeuvres, the US military said.

Russia has not recovered the drone and the jet was likely damaged, the Pentagon said.

“In fact, this unsafe and unprofessional act by the Russians nearly caused both aircraft to crash,” US Air Force General James Hecker, who oversees the US Air Force in the region, said in a statement.

Russia’s defence ministry denied that its aircraft had come into contact with the unmanned aerial vehicle (UAV), which it said had crashed after “sharp manoeuvring”. It said the drone had been detected near the Crimea peninsula, which Moscow annexed from Ukraine in 2014.

“The Russian fighters did not use their onboard weapons, did not come into contact with the UAV and returned safely to their home airfield,” the defence ministry said.

The accounts of the incident in the Black Sea, which is bordered by Russia and Ukraine among other countries, could not be independently verified.

NATO’s Supreme Allied Commander Europe, US Army General Christopher Cavoli, briefed NATO allies about the first such episode since Russia’s invasion of Ukraine in February 2022.

“We have been flying over that airspace consistently now for a year … and we’re going to continue to do that,” said White House National Security Council spokesperson John Kirby.

The US State Department later said it had summoned the Russian ambassador to protest what it called the downing of the drone.

On the front lines of eastern Ukraine, Russian troops pushed forward in waves and President Vladimir Putin reaffirmed his view that Russia’s very existence as a state was at stake in the war.

In the eastern Donbas region, Russia and Ukraine are locked in the bloodiest infantry battle in Europe since World War II after Moscow launched a winter offensive.

Putin has framed Moscow’s year-long “special military operation” as a defensive pushback against what he sees as a hostile West bent on expanding into territories historically ruled by Russia.

“So for us this is not a geopolitical task, but a task of the survival of Russian statehood, creating conditions for the future development of the country and our children,” Putin said during a visit to an aviation factory in Buryatia, some 4400 kilometres east of Moscow.

Putin accuses the West of using Ukraine as a tool to inflict “strategic defeat” on Russia. Ukraine and its Western allies say Moscow is waging an unprovoked war of conquest that has destroyed Ukrainian cities, killed thousands of people and forced millions more to flee their homes.

The Kremlin said Kyiv must accept “new realities” – its shorthand for Russia’s claim to have annexed four regions, or nearly a fifth of Ukraine’s territory.

“We have to achieve our goals. Right now this is only possible by military means due to the current position of the Kyiv regime,” Russian state news agencies quoted Kremlin spokesman Dmitry Peskov as saying.

In a video address, President Volodymyr Zelenskiy said Ukraine’s “future is being decided” in battles in the east, including the ruined city of Bakhmut.

Fighting has raged there for eight months and Ukrainian commanders say they are killing enough Russian attackers to justify carrying on despite being almost surrounded.