Moscow warned Washington to stay out of its airspace after a US drone was intercepted by Russian jets and crashed into the Black Sea, the first known direct confrontation between the superpowers since Russia invaded Ukraine.

The incident, which occurred in international airspace near territory Russia claims to have annexed from Ukraine, was blamed on both Washington and Moscow. Moscow saw it as proof that the US was directly involved in the war, while Washington saw it as an act of Russian recklessness.

Russia said it would try to recover the drone wreckage from the sea. Washington said it might never be recovered, and steps had been taken to ensure Russia could not gain intelligence from the wreckage.

“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 U.S. military said two Russian Su-27 fighter planes had approached one of its MQ-9 Reaper drones on a reconnaissance mission over international waters. The fighters harassed the drone and sprayed fuel on it, before one clipped the drone’s propeller, causing it to crash into the sea.

“This incident demonstrates a lack of competence in addition to being unsafe and unprofessional,” said James B. Hecker, commander of U.S. air forces in Europe.

White House spokesman John Kirby said U.S. officials had told Russia’s ambassador Anatoly Antonov that Moscow must be more careful: “The message was: Don’t do this again.”

According to Russia’s account, there was no collision. The drone crashed after making “sharp manoeuvres”, having “deliberately and provocatively” flown close to Russian air space. Moscow had scrambled its fighters to identify it.

“The unacceptable activity of the U.S. military in the close proximity to our borders is a cause for concern,” Antonov, the ambassador, said in a statement, accusing Washington of using drones to “gather intelligence which is subsequently used by the Kyiv regime to strike at our armed forces and territory”.

“Let us ask a rhetorical question: if, for example, a Russian strike drone appeared near New York or San Francisco, how would the U.S. Air Force and Navy react?” he said, calling on Washington to “stop making sorties near the Russian borders”.

The Kremlin said there had been no high-level contacts with Washington over the incident, describing bilateral relations as “lamentable”.

Kyiv, for its part, said the incident showed Moscow was willing to “expand the conflict zone” to draw in other countries. Russia was raising the stakes as it faces “conditions of a strategic defeat” in Ukraine, tweeted Oleksiy Danilov, secretary of Ukraine’s National Security and Defence Council.

The United States conducts regular surveillance flights in international air space in the region. It 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 Moscow portrays as a conflict against the combined might of the West.

ZELENSKIY COMMITS TO HOLDING BAKHMUT

Moscow has waged a winter offensive involving hundreds of thousands of freshly called-up reservists and convicts recruited from jail as mercenaries. It is trying to capture the small eastern city of Bakhmut to secure its first substantial victory in more than half a year.

Kyiv had appeared likely last month to be preparing to pull out of the city but has since doubled down on defending it, saying it is exhausting Russia’s attacking force there to pave the way for its own counter-attack.

Ukraine’s President Volodymyr Zelenskiy said in an overnight address that he had met his top military brass and they unanimously advised reinforcing Bakhmut.

Some Western and Ukrainian military experts have questioned whether it makes sense for Kyiv to hold on there, because of its own heavy losses there.

But Ukrainian Deputy Defence Minister Hanna Malyar said the defence of Bakhmut was important because a “large amount of enemy material is being destroyed … A huge number of troops are being killed and as of today, the enemy’s capacity to advance is being reduced.”

The front lines in Ukraine have barely moved for four months despite fighting that has evolved into Europe’s bloodiest infantry battle since World War Two, described by both sides as a “meat grinder” with battlefields strewn with dead.

Russia’s assaults have largely failed across most of the front line, apart from Bakhmut where it has captured the east of the city and advanced north and south as it tries to encircle it.

Intense fighting has also been under way further north, where Russia is trying to recapture territory it lost to a Ukrainian counter-offensive last year, and further south, where Moscow took heavy losses in failed assaults on the Ukrainian-held bastion of Vuhledar in February.

Since recapturing swathes of territory in the second half of 2022, Ukraine has lately kept to the defensive, planning a counter-offensive later this year once muddy ground dries and Western armoured vehicles and tanks arrive.

Russia invaded its neighbour a year ago, describing Ukraine as a security threat. It claims to have annexed nearly a fifth of Ukrainian territory. Kyiv and the West consider it an unprovoked war to seize land.

Tens of thousands of Ukrainian civilians and troops on both sides are believed to have been killed. Ukrainian cities have been destroyed and millions of people have fled their homes.