The People's Liberation Army (PLA) Air Force conducted its routine air patrol in China's recently established East China Sea Air Defense Identification Zone (ADIZ) on Thursday, according to a spokesman for the force.

Shi Jinke, spokesman for the People's Liberation Army Air Force, said that the patrol mission was carried out by several fighter jets and an early warning aircraft. He stressed that the mission was "a defensive measure and in line with international common practices."

Shi said China's air force is "on high alert and will take measures to deal with diverse air threats to firmly protect the security of the country's airspace."

On Thursday, Japan's military firmly insisted its own patrols over the area wouldn't stop because of Beijing's declaration.

"We have no intention to change this operation in consideration for China," Japanese Chief Cabinet Secretary Yoshihide Suga told reporters. "We will continue the surveillance/patrol operation with strong determination to protect our territory against China's one-sided attempt to change the status quo by force."

Earlier this week, Washington sent two unarmed B-52 bombers through the airspace without first informing Beijing, just two days after China's announcement that it was establishing an ADIZ according to accepted international practice.