Japan has scrambled fighter jets after at least one Chinese state-owned aeroplane entered airspace over islands at the centre of a dispute between Tokyo and Beijing.
F-15 jets were mobilised after Chinese maritime aircraft entered airspace over the Senkaku islands, which China calls the Diaoyus, just after 1pm AEDT, Chief Cabinet Secretary Osamu Fujimura told reporters on Thursday.
Chinese government ships have moved in and out of waters around the islands for more than two months, but this is the first time since the dispute flared that Tokyo has claimed any airborne incursion into what it says is Japanese territory.
Such confrontations have become commonplace since Japan nationalised the East China Sea islands in September, a move it insists amounts to nothing more than a change of ownership of what was already Japanese territory.
But Beijing reacted with fury, with observers saying the riots that erupted across China had at least tacit backing from the Communist Party government.
Thursday marks the 75th anniversary of the beginning of an episode known as the Nanjing Massacre, when Japanese Imperial Army troops entered the then-capital of China and embarked on an orgy of violence.