Japan doubles number of ships around disputed Diaoyu Islands after China sends vessels to the area

Japan is to double the size of its naval presence in waters around a set of disputed islands that are also claimed by China.

Less than a week after two ships from China's coastguard entered a zone around the Diaoyu Islands that Japan claims as the Senkaku Islands, Tokyo announced that it would dispatch a further six of its own coastguard ships to the region.

Six Japanese patrol vessels are already tasked with protecting Japan's claimed territory but there are growing concerns about increasing Chinese assertiveness.

When the Chinese crews of the Haijing 2307 and 2337 were challenged last week by a Japanese coastguard ship, they replied the islands were the "inherent territory of China" and that the surrounding waters were also Chinese.

Yoichi Shimada, a professor of international relations at Fukui Prefectural University, said the commitment of additional maritime forces by Tokyo was "long overdue".

"More and more people around the world are recognising just how assertive and aggressive China is being in making territorial demands, especially in regard to their actions in the South China Sea," he said.