The US state department summoned the Russian ambassador as the Kremlin denied that its plane was responsible.

US officials said the MQ-9 Reaper surveillance and reconnaissance drone was in international airspace when two Russian Su-27s fighters approached it.

They flew near it for 30 to 40 minutes, repeatedly moved in front of it, and dumped fuel on the drone in an apparent attempt to disrupt its flight.

One of the jets then moved behind the drone and got so close it hit the unmanned US aircraft’s propeller, which is at the back.

Operators controlling the drone from a US base were forced to bring it down in international waters.

It was the first such incident since Russia’s invasion of Ukraine a year ago.

The US drone came down west of Crimea, and the Russian jets reportedly landed nearby, according to US officials.

US officials said the Russian pilots’ actions had been “unsafe, unprofessional, environmentally unsound”, and showed a “lack of competence”.

The White House said it was not immediately clear if the Russian pilots had intended to down the drone.

Retired Brigadier General Mark Kimmitt said: “When you’re dumping fuel from your aircraft, that’s a serious effort to try to bring that thing down. This isn’t escalatory unless we want to make it escalatory. I hope everyone takes a deep breath.”

Others suggested the Russian pilots were probably only intending to “buzz” the drone and pressurise its remote operator, but one of them got too close.

The Pentagon said the Su-27 that hit the drone almost crashed after the collision.

A Pentagon spokesman said the drone had not been recovered by the Russians.

Russia’s defence ministry said the drone crashed because of “sharp manoeuvring”.

It said: “The Russian fighters did not use their onboard weapons, did not come into contact with the [drone] and returned safely to their home airfield.”

The US summoned the Russian ambassador in Washington to protest about the crash.

Drones and other US and British aircraft have been collecting intelligence over the Black Sea for months.

John Kirby, the White House National Security Council spokesman, said it was “not uncommon” to have intercepts, when one aircraft makes
visual or electronic contact with another.

He said there had been other intercepts over the Black Sea in recent weeks.

But this case was “unique” because it had resulted in the “splashing” of the US drone.

Mr Kirby said that if the Russians had been trying to send a message about not flying in the area, it would not work.

He said: “If the message is that they want to deter or dissuade us from flying and operating in international airspace over the Black Sea, then that is not going to happen.

“We are going to continue to fly and operate in international airspace over international waters.”

He added: “We don’t need to have some sort of check-in with the Russians before we fly in international airspace.”

Reapers have a 20-metre wing-span and can fly at an altitude of up to 17,000m. They are used for surveillance and reconnaissance, as well as intelligence collection in support of strikes.

Several have been lost in recent years, including some to hostile action.

One was brought down in 2019 over Yemen with a surface-to-air missile fired by Houthi rebels.

In the same year, Iran shot down a US drone flying over the Strait of Hormuz.

Last year, a Reaper reportedly crashed in Libya and another went down during a training exercise in Romania.

The Pentagon said the latest incident came in the wake of a pattern of dangerous behaviour by Russian pilots operating near aircraft flown by the US and its allies, including over the Black Sea.

A spokesman for the US European Command said: “These aggressive actions by Russian aircrew are dangerous and could lead to miscalculation and unintended escalation.”