The North American Aerospace Defense Command said that it spotted Russian military aircraft flying near Alaska on Tuesday, with Russia’s Defense Ministry later confirming its air force carried out a routine patrol in the area.

While the aircraft did not enter U.S. or Canadian sovereign airspace, NORAD said it did enter the Alaskan Air Defense Identification Zone, a stretch of international airspace where foreign aircraft are monitored for national defense purposes.

NORAD did not specify the number or type of aircraft involved, but emphasized that the activity was “not seen as a threat.” Russian military flights in the area occur regularly and are closely tracked, the command said.

According to a statement later issued by Russia’s Defense Ministry, Tu-95MS strategic bombers carried out a planned 15-hour patrol over international waters of the Bering Sea.