Russia has conducted its first airstrike in Syria, near the city of Homs, a senior US official told CNN on Wednesday.

Russia has conducted its first airstrike in Syria, near the city of Homs, a senior US official told CNN on Wednesday.

The Russians told the United States that it should not fly US warplanes in Syria, but gave no geographical information about where Russia planned to strike. The senior official said U.S. missions are continuing as normal.

Earlier Wednesday, the upper house of the Russian parliament gave President Vladimir Putin approval to use the air force in Syria, according to state media.

"The Federation Council unanimously supported the President's request -- 162 votes in favor of granting permission," Kremlin Chief of Staff Sergey Ivanov said, according to ITAR-Tass.

After several days of familiarization flights, and the collection of potential targeting information by drones, the Russian air force was known to be ready.

Four Russian Su-34 Fullback fighter jets are now at the Latakia air base in Syria, and more than 600 Russian troops are in place, CNN said.

Pentagon spokesman Peter Cook told reporters Tuesday that Secretary of Defense Ash Carter directed his staff to "open lines of communication with Russia on de-confliction."

The timing of these discussions is to be worked out in the coming days. The purpose of the discussions is "to ensure the safety of coalition air crews," he said.

Cook added that the two nations have common ground when it comes to fighting ISIL with Carter making clear that "the goal should be to take the fight to ISIL and not to defend the Assad regime."