JUNEAU, Alaska (AP) — Two Russian aircraft that came within 50 miles (80 kilometers) of Unimak Island along Alaska’s Aleutian chain were intercepted late Wednesday, military officials said Thursday.

The incident marked the fifth time this month that such an intercept has taken place, Gen. Terrence J. O’Shaughnessy, commander of the North American Aerospace Defense Command, said in a release.

NORAD said the Russian aircraft did not enter U.S. or Canadian airspace during the roughly four-hour flight in the region. The Russian planes were identified as IL-38 maritime patrol aircraft.

Capt. Cameron Hillier, a NORAD spokesperson, said this is the ninth such incident off Alaska or Canada this year. He said all the interactions are “safe and professional.”

Since Russia resumed long-range aviation activities in 2007, there has been an average of around seven intercepts a year, though the number in any given year has been zero to 15, Hillier said.