The Pentagon says U.S. aircraft have had to change course to avoid colliding with Russian planes in Syria, sparking worries about an international incident.
Officials said Wednesday there had been at least one such close call in the last week, following Russia's launch of airstrikes in Syria.
The danger of a military accident involving service members of the two nations — both of which are operating in Syrian airspace — has grown as defense talks between the U.S. and Russia stall.
CBS News reported that Russian aircraft have come within 20 miles of U.S. aircraft, and only a "handful" of miles from American drones.
Russia is also posing a threat to U.S. aircraft in Iraq, where the Pentagon is also carrying out strikes against the Islamic State in Iraq and Syria (ISIS).
Russia on Wednesday launched cruise missiles from ships in the Caspian Sea into Syria — which traveled through Iraqi airspace, where U.S. and coalition air forces are flying.
Over the weekend, Russia also violated Turkish airspace, from where the U.S. and coalition forces launch strikes into Syria.
And while Russia has been mostly hitting anti-regime groups in western Syria to shore up its ally, Syrian President Bashar al-Assad, on Monday it also launched strikes on ISIS in the eastern city of Palmyra. Those Russian attacks came shortly after coalition forces struck the city just a day, and possibly hours, before.
Those incidents have raised concerns, but talks between the Pentagon and the Russian Ministry of Defense are at a standstill.
Pentagon officials conducted a videoconference with their Russian counterparts on Oct. 1 — a day after Russia began airstrikes — but a second round has not yet been scheduled.
Defense Secretary Ashton Carter on Tuesday said the U.S. was awaiting a response from Russia, and urged Russian officials to act immediately.
Davis said during the first round of talks, the U.S. presented a proposal to Russia on how to avoid any unintended clashes in the airspace over Syria.
Retired Air Force Lt. Gen. Ralph Jodice, former commander of NATO Allied Air Command Headquarters in Turkey, said normally, detailed coordination takes place between forces operating in the same zone and not doing so "can be very dangerous."
"You can be operating in a piece of sky and you may not know that there's something else flying through it," said Jodice, a former fighter pilot.
The need to coordinate with Russia could become even more urgent, as Moscow prepares to deploy "volunteer" ground troops to Syria.
Russia on Sunday announced it would send ground troops into Syria, as part of its campaign to boost Assad's regime.
The presence of Russian troops, as well as a growing presence of Iranian troops, could present huge problems for U.S. and coalition forces.
U.S. and allied forces are providing air support for coalition-trained rebels, as well as groups who are fighting ISIS but also oppose Assad.
If Moscow goes after those rebel groups, there are worries about a situation in which U.S. and coalition forces accidentally hit Russian ground forces.
"We definitely have the potential to strike Russian forces," Jodice said.
Davis said for right now, U.S. forces are simply paying close attention to what they see.
“We do continue to maintain a high-level of situational awareness. We do that through a variety of means where we are knowing what is out there in our battle space in which we operate,” he said.
Jodice said that way of operating should not go on for long.
"You can't be operating on the 'big sky, little bullet' theory: The sky's pretty big, and it's just a little bullet, it'll never hit me," he said in an interview from Italy, where he is advising NATO forces.
"You need competent military commanders and staff who do this for a living," to help prevent any accidents in airspace, he said.
This story was updated at 3:10 p.m.