The US has indicated that Russia is likely to try recover debris from the US drone downed after a Russian intercept over the Black Sea on Tuesday, the Pentagon said as it played down Moscow's prospects for success.

"We do have indications that Russia is likely making an effort to try to recover MQ-9 debris... however, we assess it's very unlikely that they would be able to recover anything useful," said Brigadier General Patrick Ryder, a Pentagon spokesperson.

A US official, speaking on condition of anonymity, said Russian ships had been seen near the area where the drone had crashed, though they did not appear to have recovered any parts of the drone yet.

It was not clear if they were still in the area.

Earlier, the Pentagon released a video showing a Russian military jet intercept a US drone downed over the Black Sea two days ago, in what was the first direct encounter between the world's leading nuclear powers since the Ukraine war began.

The rare Pentagon move came a day after US and Russian defence ministers and military chiefs held phone conversations over the incident that saw the MQ-9 Reaper drone crash into the sea while on a reconnaissance mission in international airspace.

In the declassified, roughly 40-second video, a Russian Su-27 fighter jet comes very close to the drone and dumps what US officials say was jet fuel near it in an apparent effort to damage the US aircraft as it flew over the Black Sea.

It also shows the loss of the video feed after a second pass by a Russian jet, which the Pentagon says resulted from its collision with the drone.

The video ends with images of the drone's damaged propeller, which the Pentagon says resulted from the collision, making the aircraft inoperable.

The White House said the footage released refuted Moscow's version of events.

"It absolutely just decimates the Russian lie about what they said happened or what they said didn't happen," White House spokesperson John Kirby told reporters.

"It's pretty darn obvious when you look at that video that (the) fighter jet hit our drone."

Russia has denied any collision and said the drone crashed after making "sharp manoeuvres", having "provocatively" flown close to Russian air space near Crimea, which Moscow forcibly annexed from Ukraine in 2014.

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"There is a pattern of behaviour recently where there is a little bit more aggressive actions being conducted by the Russians," General Mark Milley, chairman of the US Joint Chiefs of Staff said yesterday.

He said it was clear that the intercept and harassment of the drone by Russian jets was intentional, but it was unclear whether the Russian pilots meant to slam their aircraft into the drone - a move that could also put them at risk.

Russian Defence Minister Sergei Shoigu told his US counterpart that US drone flights near Crimea's coast "were provocative in nature" and could lead to "an escalation ... in the Black Sea zone," a ministry statement said.

Russia, the statement said, has "no interest" in escalation" but will in future react in due proportion" and the two countries should "act with a maximum of responsibility", including by having military lines of communication in a crisis.

US Defense Secretary Lloyd Austin declined to offer details about his conversation with Mr Shoigu, but said the United States would continue "to operate wherever international law allows. And it is incumbent on Russia to operate its military aircraft in a safe and professional manner".

Russia has said the episode showed Washington was directly participating in the Ukraine war, something the West has taken pains to avoid.

"The Americans keep saying they're not taking part in military operations. This is the latest confirmation that they are directly participating in these activities - in the war," Kremlin Security Council Secretary Nikolai Patrushev said.

The US has supported Ukraine with tens of billions of dollars in military aid but says its troops have not become directly engaged in the war, which Russia portrays as a conflict against the combined might of the West.