The memorandum of understanding is the result of three separate conversations between military officials from both countries but a U.S. military spokesman made it clear that signing the agreement did not indicate America’s support for Moscow’s military maneuvers in Syria.

“We continue to believe that Russia’s strategy in Syria is counterproductive and their support for the Assad regime will only make Syria’s civil war worse,” said Peter Cook.

The agreement includes specific safety protocols for aircrews, conduct, the use of communication frequencies and a line of communication on the ground. Information sharing was not part of the document.

Cook said the U.S. and Russia will form a working group to discuss any implementation issues that may come up.

Russia began carrying out airstrikes in Syria late last month. The strikes are aimed at supporting the regime of Syrian President Bashar al-Assad – an ally of Russia- against Daesh, according to the Kremlin.

But Turkey and the West accuse Russia of targeting moderate groups in Syria opposed to Assad, many of which are supported by Saudi Arabia, Turkey, the US and Europe.

To avoid military conflicts in the region, the U.S. and Russian military officials on Oct. 1 began talks about air safety above Syria.

At least 250,000 people have been killed since the beginning of the Syrian conflict in 2011, with 7.6 million internally displaced and more than 4 million having fled to nearby countries.

Full details about the deal will not be made public upon the request of the Russians, according to Cook.