Protesters smashed up a Honda-made police car in Shenzen and businesses with Japanese connections were attacked across China over the weekend as activists from Japan landed on a disputed island to stake their claim. About 10 nationalists swam ashore from a flotilla of vessels at Uotsori and waved Japanese flags.

Koichi Mukoyama, a conservative MP aboard one of the boats told AP, “Four days ago there was an illegal landing on the island and as such we need to solidify and reaffirm our own territory.”

Japan controls what it knows as the Senkaku islands and last week arrested Hong Kong activists who visited the islands – to them known as the Diaoyu – in an attempt, supported by Beijing, to press their claims.

Historical tensions have taken a turn for the worse recently, with the islands a focal point for many ongoing disputes. The latest major protests in China, in Shenzen, Quingdao, Taiyuan and Hangzhou spread to smaller incidents nationwide and appear to be the largest since 2005 when, The Guardian reports, tens of thousands marched over several weekends.