Jan 24 (NHK) - Japan's Maritime Self-Defense Force says the patrol plane in question is a P3C from Kanoya Air Base in Kagoshima Prefecture.
It says the aircraft flew at an altitude of more than 150 meters and carried out surveillance in a proper manner.
The Defense Ministry says the area near Ieodo in the East China Sea is within Japan's Air Defense Identification Zone, so MSDF planes regularly patrol there.
The ministry also says when patrol planes must fly near foreign naval vessels, they must stay more than 500 meters away and maintain an altitude of 150 meters or more.