Sharjah24 - AFP: Moscow said on Wednesday that it will make an effort to find the remains of a US military drone that had crashed over the Black Sea after an incident that Washington had attributed to two Russian fighter planes.

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.