(AFP) - Moscow said Wednesday it would try to retrieve the wreckage of a US military drone that crashed over the Black Sea in a confrontation Washington blamed on two Russian fighter jets.

Russia also warned that it would react "proportionately" to any future US "provocations" as tensions simmered and Moscow denied its Su-27 military aircraft had clipped the propeller of the unmanned Reaper drone.

But Washington was unbowed, with Defence Secretary Lloyd Austin telling his Russian counterpart Sergei Shoigu that the United States would continue flying "wherever international law allows."

Moscow confirmed the call and said Washington had initiated it.

Russia's defence ministry said US drone flights off the coast of Crimea "are provocative in nature, which creates preconditions for an escalation of the situation in the Black Sea zone," while Kyiv suggested the incident was evidence the Kremlin wanted to draw the United States into the Ukraine conflict.

Russian Security Council secretary Nikolai Patrushev said in televised remarks Moscow would seek to retrieve the downed craft but was unsure if the effort would be a success.

"It has to be done. And we will certainly work on it," he said.

But General Mark Milley, the chairman of the US Joint Chiefs of Staff, told journalists that any recovery effort would be difficult, as the drone likely broke up and sank in an area where the water is 4,000-5,000 feet (1,200-1,500 metres) deep.

Even if Russia was able to recover the wreckage, the United States took "mitigating measures" to protect sensitive information.

"We are quite confident that whatever was of value is no longer of value," Milley said.

The crash on Tuesday, which Washington said was the fault of reckless and unprofessional Russian conduct, further ratcheted up tensions between Moscow and Western allies, already soaring over the Ukraine conflict.

Patrushev said the incident was proof that the United States is a direct party to fighting between Moscow and Kyiv and said Russia had a responsibility to "defend our independence and our sovereignty".

Russia's defence ministry said it had scrambled jets after detecting a US drone over the Black Sea, but denied causing the crash, saying the aircraft had lost control.

The Pentagon said the drone was on a routine mission when it was intercepted "in a reckless, environmentally unsound and unprofessional manner" and White House national security spokesman John Kirby refuted Russia's denial.

- Regular intercepts-

Russian intercepts over the Black Sea are common, Kirby said, but this one was particularly "unsafe and unprofessional" and "reckless".

Ukraine said the incident was "provoked by Russia" and cautioned that it signalled President Vladimir Putin's aim to "expand the conflict".

"The purpose of this all-in tactic is to always be raising the stakes," Ukrainian National Security and Defence Council secretary Oleksiy Danilov said on social media.

NATO diplomats in Brussels confirmed the incident, but said they did not expect it to immediately escalate into a further confrontation.

A Western military source, speaking to AFP on condition of anonymity, said diplomatic channels between Russia and the United States could help limit any fallout.

Russia's campaign in Ukraine has led to heightened fears of a direct confrontation between Moscow and the NATO alliance, which has been arming Kyiv to help it defend itself.

Reports of a missile strike in eastern Poland in November briefly caused alarm before Western military sources concluded it was a Ukrainian air defence missile, not a Russian one.

- 'Unflyable and uncontrollable'

The United States uses MQ-9 Reapers for both surveillance and strikes and has long operated them over the Black Sea to keep an eye on Russian naval forces.

Pentagon spokesman Brigadier General Pat Ryder said the drone was "unflyable and uncontrollable so we brought it down", adding that the collision also likely damaged the Russian aircraft, which he said was able to land following the incident.

Several US Reapers have been lost in recent years, including to hostile fire.

One was shot down in 2019 over Yemen with a surface-to-air missile fired by Huthi rebels, the US Central Command said at the time.

Reapers can be armed with Hellfire missiles as well as laser-guided bombs and can fly for more than 1,100 miles (1,770 kilometres) at altitudes of up to 15,000 metres (50,000 feet), according to the US Air Force.

© Agence France-Presse