Moscow and Washington exchanged warnings and accusations after the United States said a Russian combat aircraft had sent one of its spy drones plunging into the Black Sea, where tension is high due to the Kremlin’s invasion of Ukraine and occupation of the Crimean peninsula.

Washington said “reckless” behaviour by the pilots of two Russian Su-27 fighter jets led to one of them colliding with an MQ-9 surveillance drone on Tuesday, causing it to crash in international waters. Moscow said there was no collision before the drone came down and accused the US of flying the craft into an area of increased security near Crimea.

Rancour between the nuclear powers may well extend to the fate of the wreckage, with Russia aiming to salvage the high-tech drone at a time of growing co-operation in military and other spheres with US adversaries China and Iran.

“This hazardous episode is part of a pattern of aggressive, risky and unsafe actions by Russian pilots in international airspace,” US defence secretary Lloyd Austin said on Wednesday.

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“So make no mistake: the United States will continue to fly and to operate wherever international law allows. And it is incumbent upon Russia to operate its military aircraft in a safe and professional manner.”

After being summoned to the US state department following the drone crash, Russia’s ambassador to Washington Anatoly Antonov said: “The unacceptable actions of the United States military in the close proximity to our borders are cause for concern.”

He added: “We are well aware of the missions such reconnaissance and strike drones are used for … they gather intelligence which is later used by the Kyiv regime to attack our armed forces and territory.

“We proceed from the fact that the United States will … stop making sorties near the Russian borders. We perceive any actions involving the use of American weapons and military equipment as openly hostile.”

The Kremlin said Russian president Vladimir Putin was briefed on the incident but had no plans to discuss it with US counterpart Joe Biden.

“As for bilateral relations, we know they are at probably their lowest point, in a really lamentable state,” said Kremlin spokesman Dmitry Peskov.

The White House says the drone fell into international waters, but its national security spokesman John Kirby told CNN: “I’m not sure that we’re going to be able to recover it.”

“I mean, where it fell into the Black Sea – very, very deep water … We did the best we could to minimise any intelligence value that might come from somebody else getting their hands on that drone,” he said.

Washington will not want an advanced surveillance drone to fall into Russia’s hands as it deepens ties with China and Iran. The three states are now conducting joint naval drills in the Gulf of Oman, and US officials think Moscow has sent some western weapons captured in Ukraine to Tehran for analysis and possible reverse engineering.

Russian security council secretary Nikolai Patrushev said of the drone: “I don’t know if we will manage to get it or not, but … we will certainly work on this.”