Japan's Defense Ministry says two Russian fighters briefly intruded into Japanese airspace off the northern tip of the island of Hokkaido.

Ministry official Yoshihide Yoshida says the intrusion Thursday, which lasted less than a minute, caused Japan's air force to scramble.

Yoshida says it was not immediately known whether the airspace violation was intentional or accidental, but that it was "extremely problematic."

He says the last intrusion by Russian jets in Japanese airspace was on Feb. 9, 2008.