The Japan Times on Oct 19 said Japan decided to cancel the drill in fear of provoking a negative reaction from China, while Japan's Defense Ministry said the drill preparation is still underway in another place.

Feng Wei, an expert on Japanese studies at Fudan University in Shanghai, said the hesitation may come from US efforts to strike a balance between China and Japan. "Washington doesn't want to infuriate China or threaten regional stability, but it also keeps supporting Tokyo as a leverage to contain China."

Yang said, "We will keep a close eye on developments concerning the issue."

Military ties between the two Asian powers have plunged since Tokyo in September announced the so-called purchase of the Diaoyu Islands, which have belonged to China since ancient times.

The Japanese newspaper Yomiuri Shimbun on Sunday cited an anonymous source accusing China of shelving a maritime defense communication mechanism between bilateral defense authorities. The mechanism was scheduled to be established by the end of this year.

Japan should take full responsibility for the currently severe China-Japan ties due to its illegal purchase, said Yang, urging Japan to correct its mistakes.

Despite being under mounting pressure as a result of the standoff, Japan will hardly abandon its hard-line stance on the islands and may bring more clashes to the region, said analysts. Yang did not directly respond to a question about whether the islands issue has entered a military stage, but he reiterated that the Chinese military's determination to safeguard territorial integrity and maritime rights is unshakable.

Foreign Ministry spokesman Hong Lei on Thursday confirmed that Chinese maritime surveillance ships, in routine patrols, had entered the 12-nautical-mile zone around the islands, saying it was a normal activity for Chinese surveillance ships to exercise jurisdiction over the waters.

Shen Shishun, an expert on Japanese studies at Haikou College of Economics in Hainan province, said that Chinese vessels entering the zone represented an advancement in safeguarding sovereignty.