Since Tokyo Governor Shintaro Ishihara announced his proposal to "purchase" the Diaoyu Islands, quite a few Japanese politicians have continued provocative acts against China over the isles.

Despite the obvious damage to China-Japan relations, the Japanese government seems indifferent and has failed to take any action to curb such provocative words and deeds.

Recent developments indicate that the Japanese government has shifted its attitude concerning Ishihara from "silent approval" to open support.

Uichiro Niwa, the Japanese ambassador to China, was asked by Japan's Foreign Ministry to apologize after he told media about his concerns over the ugly consequences of the "purchase plan."

It does not take an expert eye to see that the intolerance of Niwa's candid remarks by the Japanese government signals its increasing assertiveness over the Diaoyu Islands, which have been an integral part of the Chinese territory since ancient times.

In another case, Tokyo recently allowed Japanese lawmakers to "fish" in the waters around the Diaoyus, an obvious deviation from its decades-long practice of limiting Japanese citizens' visits to the islands.

Clearly, the escalation of the provocations on the islands stems from the encouragement and even support of the Japanese government.

Such unilateral actions and escalation of provocation by the Japanese could not only harm China-Japan relations, but also threaten the very foundation of their bilateral ties. If unchecked, they could even wreak havoc on the stability in East Asia.

However, one thing is for sure: The farce staged by the Japanese rightists over the Diaoyus will by no means change the fact that China has indisputable sovereignty over the islands.

It's high time the Japanese government took concrete action to put an end to the provocations, so as to ensure the smooth development of China-Japan relations in the long run.