Pentagon spokesman Peter Cook said that although the Russian government insisted that the text of the agreement remain secret, it lays out safety protocols, specifies which frequencies both sides should use to communicate, sets up a hotline on the ground and establishes a working group to talk out further issues.
Cook told reporters that the agreement does not include zones of cooperation or sharing of target information.
Russia began flying bombing missions in cooperation with the Syrian government earlier this month. The U.S. leads an international coalition that is conducting airstrikes against Islamic State in Iraq and the Levant (ISIL) targets in Syria.
In Moscow, Russia's Deputy Defense Minister Anatoly Antonov said in a statement carried by Russian news agencies that signing the memorandum was a positive step that has "important practical meaning."
Antonov said Russian and U.S. military officials will set up round-the clock communications channels and "determine the mechanism of interaction, including mutual assistance in crisis situations."
"The Americans have promised to get the agreed rules to all participants of the anti-IS[IL] coalition they lead, so that their pilots proceed from those agreements," he said.
He said the memorandum "doesn't change the principled position of Russia."
The Associated Press