The United States uses MQ-9 Reapers for both surveillance and strikes and has long operated over the Black Sea keeping an eye on Russian naval forces.
“Our MQ-9 aircraft was conducting routine operations in international airspace when it was intercepted and hit by a Russian aircraft, resulting in a crash and complete loss of the MQ-9,” said US Air Force General James Hecker, commander of US Air Forces Europe and Air Forces Africa.
“In fact, this unsafe and unprofessional act by the Russians nearly caused both aircraft to crash.
“US and allied aircraft will continue to operate in international airspace and we call on the Russians to conduct themselves professionally and safely,” he added.
The US statement said that pilots had brought the Reaper down in international waters, while the US Naval Institute said it had crashed off the coast of Odesa in southeast Ukraine.
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.
According to media reports, a US MQ-9 crashed in Libya in 2022, while another went down during a training exercise in Romania earlier in the same year.
Reapers can be armed with Hellfire missiles as well as laser-guided bombs and can fly for more than 1,770km at altitudes of up to 15,000m, according to the US Air Force.