Japan scrambled fighter jets after China for the first time flew military aircraft through the international airspace near Japan’s southernmost islands, the latest incident straining ties in East Asia.

“I believe this indicates China's move toward further maritime expansion,” Japanese Defense Minister Itsunori Onodera told reporters.

The Chinese Y-8 Early Warning aircraft flew through airspace between Okinawa prefecture's main island and the smaller Miyako Island in southern Japan out over the Pacific at around noon and later took the same route back over the East China Sea.

Earlier, Chinese coast guard ships were seen in the area near the Senkaku Islands, which Japan has controlled for well more than 100 years, but China claims in the last couple of decades.  The waters are lucrative for fishers and the sea floor beneath might hold big oil and gas reserves.

Aircraft and ships from the two countries have been shadowing each other in the area, but this is the first incident since hawkish Japanese Prime Minister Shinzo Abe won a decisive victory in upper house elections on Sunday.