The US Defense Department has released video footage which it says captured the moment when a Russian fighter jet struck a US unmanned aircraft over the Black Sea.

The Pentagon released the footage on Thursday, saying it was taken by the reconnaissance drone flying over the sea on Tuesday.

The US military says two Russian jets harassed their MQ-9 drone before one of them struck the drone's propeller. Officials said US forces had to bring the drone down in international waters as it became uncontrollable.

The footage shows a fighter plane that appears to belong to the Russian military approaching the drone and releasing white smoke presumed to be fuel as it was passing. The fighter then overtakes the US aircraft.

The footage shows a similar approach by a fighter jet before the video feed is disrupted. It then shows the drone's propeller damaged partially.

The US military denounced Russia, calling its pilots' actions dangerous.

Russia's defense ministry has denied the US claims, insisting that its aircraft did not collide with the drone.