US defense officials are reporting that on Wednesday, a pair of F-22 stealth fighters “intercepted” Russian planes in far eastern Syria, near the last ISIS-held villages which are being contested.

The incident lasted several minutes and involved the US planes firing warning flares at the Russians, forcing the Russians to retreat out of what US officials described as “coalition airspace.” It’s not clear, given the US coalition was never invited to be in Syria in the first place, that any of Syrian airspace actually belongs to the coalition.

The Russian Defense Ministry said the planes were Su-25 jets, and that they were escorting a humanitarian aid convoy. They denied that the incident amounted to an “interception,” and said that a Su-35 fighter was dispatched to protect the Su-25s from the American warplanes.

Russian officials also say the US fighters carried out mid-air maneuvers designed to simulate a fire-fight with the Russian Su-25s, though it does not appear that in this case they got in any sort of conflict with the more advanced Su-35.

This comes just days after a report that a F-22 had nearly shot down a Su-35 over the Euphrates River in the same area, which the Su-35 was protecting bombers engaged in anti-ISIS runs. Russia confirmed complaining about the incident, while the Pentagon denied that it happened.