Top defense officials from the US and Russia discussed issues relating to military safety in Syrian air space during a video conference, as the two states conduct separate airstrikes against extremists over Syria, the Pentagon said.

“The two sides discussed measures to enhance operational safety ... including the means to avoid accidents and unintended confrontation between coalition and Russian forces whenever the two sides operate in close proximity,” Pentagon Press Secretary Peter Cook said in a statement that was published on the Pentagon’s website.

According to the statement, Russian and the US military officials discussed the “ongoing implementation of the US-Russia memorandum of understanding (MOU) on flight safety over Syrian airspace” as well as measures to enhance operational safety for both sides including “the means to avoid accidents and unintended confrontation between coalition and Russian forces whenever the two sides operate in close proximity.”

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The statement also said the two sides have agreed to continue discussions in such format in the future.

Thursday’s video conference between the Pentagon and Russia’s Defense Ministry was the first since the MOU was signed in October of 2015.

Russia’s military planes have repeatedly been exposed to close encounters with unmanned aircraft, including the US drones, since beginning its aerial campaign against Islamic State (IS, former ISIS/ISIL) in Syria. The presence of various aircraft in Syrian airspace, including military cargo planes, warplanes, UAVs, and strike drones, has been a source of concern for the Russian Defense Ministry.

At the same time, the US military has claimed that at least one American military aircraft had been forced to divert its route while flying over Syria to avoid making contact with a Russian warplane. According to some unconfirmed reports in the US media, Russian fighter jets have even “intercepted” US MQ-1 Predator drones over Syria. However, data suggests that the drones’ flight paths had not been hampered, despite close fly-bys.

Why hello there! Suspected US drone spotted by Russian pilot in #Syria (VIDEO) https://t.co/HtcIS427lIpic.twitter.com/KFVQiaDh6C — RT (@RT_com) October 20, 2015

In view of mutual safety concerns, the two countries reached an agreement aimed at regulating the operations of their respective Air Forces in area, although the US had been reluctant to cooperate with Russia at first.