The United States and Russia have signed an agreement that sets the baseline rules for air safety measures in Syrian airspace, in order to minimize the risks of pilots from the two countries accidentally interfering with one another as they conduct separate bombing campaigns, the Pentagon said Thursday.

"With today's signatures, the memorandum of understanding is now in effect," Pentagon Press Secretary Peter Cook told reporters, according to the AFP. "That was signed a short time ago, earlier today." 

The Russian media also reported that the memorandum had been signed by officials from the two nations.

"The memorandum contains a number of rules and restrictions aimed at preventing incidents between American and Russian plans," said Deputy Defense Minister Anatoly Antonov.

The memo includes protocols for air crews in Syrian skies, along with a ground communications link, reported Sky News. However, the pact doesn't include zones of cooperation or sharing target information, Cook noted, adding that Moscow insisted the text of the agreement to not be made public.

Syrian skies have become crowded as of late, as the U.S., Russia and the Assad regime launch airstrikes on various "enemy factions," that have participated in the country's four-year-long civil war.

This agreement is a direct response to the increased traffic, and comes after the U.S. and Russia have had several close calls with one another within Syrian airspace, reported Newsmax. Officials report Russian planes have flown near a U.S. drone, and claim the U.S. military has had to reroute several flights to avoid any close calls with the other superpower.

As the two reach an agreement on how to interact with one another in the skies, the two will soon need to address who they attack on the ground. Whereas Russia claims to be targeting the Islamic State and other "terrorists," the Pentagon claims it's targeting non-IS rebels fighting government forces loyal to the Assad regime.