The Pentagon blamed a Russian fighter jet for the crash of a U.S. spy drone into the Black Sea on Tuesday, Reuters reported.

Two Russian Su-27 jets carried out what the U.S. military described as a reckless intercept of the MQ-9 "Reaper" drone in international airspace before one of them collided with it at 7:03am (06:03 GMT), causing the drone to crash into the sea.

Several times before the collision, the Russian fighter jets dumped fuel on the MQ-9, possibly trying to blind or damage it, and flew in front of the unmanned drone in unsafe maneuvers, the U.S. military said.

Russia has not recovered the drone and the jet was likely damaged, the Pentagon said.

"In fact, this unsafe and unprofessional act by the Russians nearly caused both aircraft to crash," U.S. Air Force General James Hecker, who oversees the U.S. Air Force in the region, said in a statement.

"We have been flying over that airspace consistently now for a year ... and we're going to continue to do that," said White House National Security Council spokesperson John Kirby.

The United States summoned Russia's ambassador to Washington on Tuesday after a Russian fighter jet downed a U.S. military drone over the Black Sea, State Department spokesperson Ned Price said.

The U.S. ambassador to Moscow has conveyed a strong message to Russia's foreign affairs ministry and U.S. officials had briefed allies and partners about the incident, Price told reporters on a phone briefing.

"We can confirm Ambassador (Anatoly) Antonov was summoned to the State Department this afternoon to meet with Assistant Secretary for European and Eurasian Affairs Karen Donfried to discuss Russia’s unsafe and unprofessional operations over the Black Sea, which resulted in the downing today of an unmanned U.S. aircraft," a senior State Department official said.

Calling the incident a "brazen violation of international law," Price declined to say what response U.S. ambassador Lynne Tracy in Moscow received from the Russians when she conveyed Washington's protest.