The Pentagon is downplaying the rising tensions between the U.S.-led coalition and the Russian-led pro-government forces in Syria, by suggesting that Moscow's angry public statements are more for show than evidence of a serious split.

"Public statement aside, we have not seen the Russians do any actions that cause us concern," said Navy Capt. Jeff Davis, a Pentagon spokesman.

Despite the Russian Defense Ministry's public threat to track U.S. planes operating west of the Euphrates River in Syria with anti-aircraft missile radar, Pentagon officials said the U.S. continues to fly in the airspace. They said one U.S. aircraft shot down an Iranian-made drone west of the Euphrates Monday night, with no Russian interference.

While the U.S. says it has made prudent adjustments to its air operations over Syrian to minimize any potential threat, the Russians have not taken any provocative actions, such as illuminating U.S. or coalition aircraft with target acquisition radars.

"We have not seen any hostile or untoward actions from the Russians," Davis said. "We have not seen anything that would cause us concern."

The Pentagon also strongly suggested that Russia is still using the de-confliction hotline that the Kremlin said was suspended after a U.S. F-15 shot down a Syrian Su-22 fighter Sunday after the jet bombed near U.S.-backed fighters in Raqqa.

The U.S. has a policy of not disclosing when the de-confliction line, which links the U.S. and Russian air operations centers, is being used. But Davis said the line is open on the U.S. end.

"We believe that having a channel where we can de-escalate and understand each other's intentions serves a very good purpose, and we are hopeful that we can continue to use it," Davis said.