Japanese authorities have arrested a group of pro-China activists who landed on the territorially disputed Senkaku Islands in the East China Sea on Wednesday.

The Japan Coast Guard arrested five activists for illegal entry before arresting the remaining nine aboard their ship. The islands are also claimed by China and are known as the Diaoyu Islands in Chinese.

The Japanese Foreign Ministry summoned China’s Ambassador to Tokyo, Cheng Yonghua, and strongly protested the activists’ move and urged China to prevent the recurrence of similar incidents.

In response, the Chinese government summoned the Japanese ambassador to China and urged for the immediate release of the 14 activists.

A group of Chinese and Hong Kong demonstrators previously landed on the islands twice in 1996 and in 2004.