The US has accused Russia of reckless behaviour after an American surveillance drone crashed into the Black Sea following an encounter with Russian fighter jets.
The US says the drone was on a routine mission in international airspace when two Russian jets tried to intercept it.
The incident highlights the increasing risk of direct confrontation between Russia and the US over the Ukraine war.
The Russian defence ministry said the drone crashed after a “sharp manoeuvre” and that the MQ-9 Reaper drone was flying with its transponders turned off. Transponders are communications devices that allow the aircraft to be tracked.
Reaper drones are surveillance aircraft with a 20m, wingspan.
According to the US military, the incident happened at about 07:03 Central European Time on Tuesday.
“Our MQ-9 aircraft was conducting routine operations in international airspace when it was intercepted and hit by a Russian aircraft, resulting in a crash and complete loss of the MQ-9,” the statement said.
Several times before the collision the Su-27 fighter jets dumped fuel on the drone in a “reckless, environmentally unsound and unprofessional manner”, it said.
The US summoned the Russian ambassador in Washington, Anatoly Antonov, to protest against the move.
Following the meeting, Russian state media quoted Mr Antonov as saying that Moscow saw the drone incident as “a provocation” and that “the unacceptable activity of the US military in the close proximity to our borders is a cause for concern”.