() For the third time in a week, American fighter jets were scrambled to respond to a Russian aircraft near Alaska on Sunday.

The North American Aerospace Defense Command said it tracked an IL-20 Coot a Russian aircraft used for surveillance into what’s called the Alaskan Air Defense Identification Zone.

Though the aircraft entered the zone, it did not enter U.S. or Canadian sovereign territory, NORAD said. The defense identification zone is over international waters, and NORAD tracks and identifies any aircraft in the zone.

NORAD dispatched two F-16 fighter jets, two KC-135 tankers and an E-3 Sentry aircraft to monitor the Russian aircraft.

Spy plane activity ‘not seen as a threat’

According to NORAD, the Russian activity near Alaska was “not seen as a threat.”

While NORAD said it is not uncommon for Russian aircraft to enter the zone and be met with an American response, it was the third such incident in the past week.

The same kind of Russian surveillance aircraft was spotted Wednesday and Thursday of last week, and NORAD scrambled military jets to monitor the Russian aircraft in both cases.