A Russian Sukhoi-27 fighter jet on Tuesday dumped fuel on an American MQ-9 Reaper drone over the Black Sea and then collided with it, causing the drone to crash.
Here's what we know so far:
The US military termed the Russian jet's manoeuvre as "reckless". "Several times before the collision, the Su-27s dumped fuel on and flew in front of the MQ-9 in a reckless, environmentally unsound, and unprofessional manner," the US military said.
Russia denied playing any role in the crash of the drone, which the US says was on a routine surveillance mission. "As a result of a sharp manoeuvre... the MQ-9 unmanned aerial vehicle entered an uncontrolled flight with loss of altitude and collided with the surface of the water," the Russian Defense Ministry said.
The US State Department summoned Russian Ambassador Anatoly Antonov for a meeting with Karen Donfried, the assistant secretary of state for Europe. "As for us, we do not want any confrontation between the United States and Russia," Mr Antonov said.
White House national security spokesperson John Kirby said the US "obviously" refutes the Russian's denial, adding that the US is trying to recover the fallen drone. "Without getting into too much detail, what I can say is that we've taken steps to protect our equities with respect to that particular drone -- that particular aircraft," Mr Kirby said as quoted by CNN.
"We are engaging directly with the Russians, again at senior levels, to convey our strong objections to this unsafe, unprofessional intercept, which caused the downing of the unmanned US aircraft," said US State Department spokesperson Ned Price.
