China's declaration of its air control zone over the East China Sea has come under strain to counter the "aggressiveness of Japan" amid an increasingly acrimonious dispute over a set of islands claimed by the two nations, a Chinese expert said Wednesday.

The territorial dispute between China and Japan has been escalating since China announced Saturday its Air Defense Identification Zone (ADIZ) over the sea that partly overlaps those of South Korea and Japan. Defying the Chinese move, the U.S. on Tuesday flew a pair of B-52 bombers through the area.

"China's establishment of an ADIZ in the East China Sea is a forced response to the aggressiveness of Japan which has threatened to fire warning shots against Chinese planes in its ADIZ," said Luo Yuan, vice president of the China Strategy Culture Promotion Association, in an op-ed piece published by the official Global Times newspaper.

"In the second quarter of this year, Japanese jets were scrambled 69 times to interfere with the normal operation of Chinese jets. During the same period of last year, the number was only 15," Luo said.

"Recently, the Japanese navy even sent warships to the waters where the Chinese navy was holding live-fire drills," Luo said.

Luo said the Chinese air zone "will help China out of its passive position."

The Chinese zone included a set of islands at the center of a territorial dispute between Beijing and Tokyo, which are known as Diaoyu in China and Senkaku in Japan. The new zone also included Ieodo, a South Korean-controlled submerged rock of .

Tension sparked in September 2012 when the Tokyo government purchased three of the disputed islands from a private owner.

China requires all aircraft entering the new zone to report to Chinese authorities and follow their instructions and that its military will take "defensive emergency measures" if a foreign aircraft does not comply with the air-zone rules. (Yonhap News)