A Russian fighter flew within a half-mile of a U.S. warplane over eastern Syria on Oct. 17, officials confirmed Friday.

Lt. Gen. Jeffrey Harrigian, commander of U.S. Air Forces Central Command, told AFP Friday that the Russian jet was escorting a large spy plane late that day when it flew dangerously close to the American plane. Harrigian said the Russian pilot likely did not see the American plane because it was dark and the planes did not have their lights on.

The incident comes at a time of high tensions between the two nations over the civil war in Syria. Harrigian also told AFP that close calls between Russian and U.S. aircraft have increased over the past six weeks, and Russian jets have "intentional near misses" with coalition aircraft about once every 10 days.

But the U.S. doesn't think the Oct. 17 incident was done "with nefarious intent," Operation Inherent Resolve spokesman Col. John Dorrian said in a Friday briefing at the Pentagon.

Dorrian described the plane as "a larger-framed [coalition] aircraft that we don't provide additional detail on." The Pentagon didn't specify what kind of Russian fighter was involved.

"The Russian jet passed in front of the coalition jet close enough that the jetwash from that flight was felt within the larger aircraft," Dorrian said. "That's closer than we like."

Dorrian said the aircraft immediately made contact with one another, and officials followed up the next day with their Russian counterparts through the hotline the nations' militaries have used to deconflict their aircraft over Syria.

AFP reported that "the American pilot tried unsuccessfully to reach the Russian jet via an emergency radio channel" during the incident.

Dorrian said military officials don't feel the close encounter was intentional, and coalition officials continue to conduct deconfliction calls with the Russians on a daily basis, as well as discussing the Oct. 17 incident. 

He also said the incident was reported up the chain of command, but said it was not publicly announced to avoid inflaming tensions in the volatile region.

"The deconfliction channel is not one that's necessarily designed for public disclosure," Dorrian said. "The purpose of that is to do the exact opposite, of turning it into a major incident. It's really more intended to keep the temperature down between us and the Russians in that very crowded and confused, at times, battle space. That's why we didn't put that out then."