Japanese Defense Ministry officials say Chinese and Russian bombers jointly flew near Japan on Friday.
They say two from each country traveled over the Sea of Japan and the East China Sea, before heading out to the Pacific Ocean.
They say the aircraft passed over waters between the main island of Okinawa and Miyako Island in southern Japan.
The officials say the bombers later returned to the East China Sea using a similar route. They say the Air Self-Defense Force scrambled fighter jets, and that the bombers did not enter Japanese airspace.
This is the third time the Defense Ministry has disclosed sightings of joint flights by Chinese and Russian forces near Japan. The last time was in December last year.
On Thursday, naval ships from the two countries were confirmed to have passed the Tsushima Strait off southwestern Japan.
Defense officials are raising their alert level amid a series of moves they describe as extraordinary.