Beijing (AsiaNews/Agencies) - After the Japanese government bought the Diaoyu/Senkaku Island, China warned it was "ready" to do everything to protect its territorial integrity. Although the archipelago has been disputed for years, the situation has become serious in the past few months.

In a front-page report, the PLA Daily said the army's navy, air force and strategic missile corps had staged joint military drills in the Yellow Sea and in the Gobi Desert early this month, detailing a string of all-weather, live-fire exercises by the Nanjing Military Command.

One of the key missions of the command is to defend the East China Sea, where the disputed islands are located.

The drills are a warning to Japan. If Tokyo "attempts to deploy its maritime self-defence force to deal with our patrol ships, we are ready to defend our national interests when any conflicts happen," said Xu Guangyu, a senior researcher at the China Arms Control and Disarmament Association in Beijing.

The value of the islands is unclear. Some believe they are strategic because they are at the crossroad of important maritime routes. Others say they have rich fishing grounds and vast gas reserves.

In 2008, as a gesture of détente, Japan and China signed an agreement to jointly develop the islands' resources, but nothing came of it.

For Japan, the islands are part of Okinawa Prefecture. A few days ago, it decided to buy them from their private owners. Beijing reacted harshly as Prime Minister Wen Jiabao said that China would not give up an inch of its territory.

Diplomatic channels now seem closed after all attempts at détente proved futile.

Even fate appears to be conspiring. The new Japanese ambassador to China, Shinichi Nishimiya, was hospitalised in Tokyo on Thursday, a day before his deployment. Foul play was not suspected.