The MQ-9 Reaper surveillance drone was brought down by the US as the Su-27 Russian jet damaged its propeller in the collision|U.S. Air Force|Public Domain

Escalating the already high tensions between the two nations, a Russian jet collided with the US Air Force’s MQ-9 Reaper drone above the Black Sea on Tuesday.

It was the first known physical contact between US and Russian aircraft since the Ukraine invasion.

The US was forced to bring the surveillance drone down as the Su-27 Russian jet damaged its propeller in the collision.

Though it is common for Russian and US aircraft to cross each above international waters like the Black Sea, this collision was particularly “unsafe and unprofessional,” said National Security Council spokesperson John Kirby.