The U.S. Defense Secretary says it’s unclear whether Russia’s jets crossed the unofficial line separating the air forces intentionally or deliberately

The U.S. Defense Secretary Jim Mattis commented on the dangerous flights of Russian fighter jets in Syria, as The Washington Post reports.

Mattis told reporters that two air forces centers are still communicating through a phone line to coordinate flight movements. Commenting on the incident with Russian jets crossing the unofficial line between two forces, Mattis said it was unclear if it was intentional or with purpose.

He also added he didn’t expect perfection in flights, but didn't want dangerous manoeuvres either.

As we reported earlier, two Russian Su-25 planes entered the airspace over the Euphrates, coming very close to the U.S. aircraft; they were intercepted by two F-22 stealth fighters, which fired the warning shots in response.