The Russian military said one of its warships in the Black Sea fired warning shots and a warplane dropped bombs Wednesday to force a British destroyer away from an area near Crimea that Moscow claims as its territorial waters, but Britain denied that account and insisted its ship wasn’t fired upon.

It was the first time since the Cold War that Moscow acknowledged using live ammunition to deter a NATO warship, reflecting the growing risk of military incidents amid soaring tensions between Russia and the West.

The Russian Defense Ministry said a patrol ship fired warning shots after the British destroyer HMS Defender had ignored a notice against intrusion and sailed 3 kilometers (1.6 nautical miles) into Russia’s territorial waters near Sevastopol, the main Russian naval base in Crimea. It said a Russian Su-24 bomber also dropped four bombs ahead of the British ship’s path to persuade it to change course. Minutes later, the British warship left the Russian waters, the ministry said.

The Defense Ministry said it summoned the U.K. military attache in Moscow to protest the British destroyer’s “dangerous move” as a “crude violation” of international maritime law. It urged British authorities to investigate its crew’s actions to “prevent such incidents in the future.”

Britain’s Ministry of Defense denied the Defender had been fired on or was in Russian waters.

“No warning shots have been fired at HMS Defender,” it said in a statement. “The Royal Navy ship is conducting innocent passage through Ukrainian territorial waters in accordance with international law.”

Russia annexed Ukraine’s Crimean Peninsula in 2014, a move that was not recognized by most countries, gaining access to the peninsula’s long Black Sea coast. Russia has frequently chafed at NATO warships visits near Crimea, casting them as destabilizing. In April, it declared a broader sea area off Crimea closed to foreign naval ships.

“We believe the Russians were undertaking a gunnery exercise in the Black Sea and provided the maritime community with prior warning of their activity,” the British Ministry of Defense said. “No shots were directed at HMS Defender and we do not recognize the claim that bombs were dropped in her path.”

British Defense Secretary Ben Wallace said the U.K. vessel “carried out a routine transit from Odessa towards Georgia across the Black Sea.”

“As is normal for this route, she entered an internationally recognized traffic separation corridor,” he said on Twitter, adding that HMS Defender exited the corridor safely at 9:45 a.m. BST (0845 GMT; 4:45 a.m. EDT).

“As is routine, Russian vessels shadowed her passage and she was made aware of training exercises in her wider vicinity,” he added.

Wallace said Britain’s ambassador in Moscow had been summoned by Russian authorities. Speaking to Parliament’s defense committee, Wallace again denied Russia’s version of events.

“These are the things that come and go with Russia,” he said. “Disinformation, misinformation is something that we have seen regularly. We’re not surprised by it; we plan for it.”