Japan is now immediately scrambling fighter jets against all Chinese military aircraft taking off from an air base in Fujian Province, as tensions continue between the two countries over the Senkaku Islands, government sources said Saturday.

Air Self-Defense Force planes have also been flying daily patrols over the East China Sea from sunrise to sunset to monitor Chinese military aircraft in the area, the sources said.

Before Japan reviewed its policy early last year, it used to only scramble fighter jets against Chinese military aircraft approaching its airspace.

Chinese fighter patrols that operate near the Senkakus used to fly out of Zhejiang province. But China has since moved the location of their base of operations closer to the islands disputed by Beijing, according to the sources.

The distance between the air base and the Japan-controlled islands is about 380 kilometers — a 20-minute flight for Chinese J-11 fighter jets.

Meanwhile, the distance between the ASDF's base in Naha, Okinawa Prefecture, from which it scrambles jets against Chinese military aircraft, is about 410 km, requiring a travel time of about 25 minutes for Japan's F-15 fighters.

The ASDF now needs to immediately respond to Chinese fighters when they leave from the air base and prevent them from entering Japan's airspace, the sources said.

Japan's air command has set a defense line at a latitude of 27 degrees north, to block Chinese military aircraft approaching near the islands, which are located between latitudes of 25 and 26 degrees north, according to the sources.

The ASDF used to respond to each Chinese military plane with two of its fighter jets. But it now does so with four, the sources said.

Japan scrambled fighter jets against Chinese military aircraft 638 times in fiscal 2018 and 675 times in the previous fiscal year through March, according to the Defense Ministry.