Recriminations fly after Russian jet downs U.S. drone

STORY: The mid-air collision between a U.S. spy drone and a Russian fighter jet in international airspace sparked fierce condemnations from Washington and denials from Moscow.

U.S. Defense Secretary Lloyd Austin on Wednesday admonished the Kremlin after a Russian Su-27 aircraft the day before intercepted, struck, and damaged the propeller of an American MQ-9 "Reaper" drone, forcing operators to crash it into the waters of the Black Sea.

"It is incumbent upon Russia to operate its military aircraft in a safe and professional manner."

American allies expressed similar alarm. Here's UK Defense Secretary Ben Wallace, who spoke on a visit to Japan:

"The key here is that all parties respect international air space. We urge the Russians to do so."

BUT Russia's Defense Ministry claimed the American drone was heading toward Russian-held territory, and said the there was no collision, asserting the MQ-9 crashed all on its own.

The Russian ambassador to the U.S. told Russian state television the drone was meant to provoke a Russian response so that American could accuse Russian pilots of unprofessionalism.

The downing of the drone marks the first incident since Russian forces invaded Ukraine over a year ago, a conflict that has seen a steadily increasing amount of U.S. weaponry - operated mostly by Ukrainians - clashing with Russian armaments.

"We've been waiting for this sort of thing to happen for some time. It's surprising it hasn't already happened."

Professor Michael Clarke is the former director-general of the Royal United Services Institute in London.

"The United States has been flying drones in open airspace across the Black Sea, as they're perfectly legally entitled to do. The Russians have been trying to disrupt them and buzz them for months. It was only a matter of time before something like this happened."

Despite Russian denials, Clark told Reuters he believed the collision was real, if unintended.

"This almost certainly, I'm ninety-nine percent certain, was an accident. Pilot error. The Su-27 pilot who can deliberately and safely fly his plane into the propeller of a Reaper drone hasn't yet been born. [flash] So I'm sure it's an accident, and that pilot's very lucky."

Clark said the promised American response will likely be to reinforce its current posture.

"America will certainly carry on running patrols, surveillance patrols, in open airspace, in internationally-recognized airspace, and the Russians, almost certainly, will continue trying to frustrate them in whatever way they can."

Russia said it would try to recover the drone wreckage from the sea. Washington said it might never be recovered, and steps had been taken to ensure Russia could not gain intelligence from the wreckage.