evidence: In 1974, as US troops withdrew from Vietnam, China invaded the Paracel Islands, called the Xisha Islands by Beijing and the Hoang Sa Islands by Hanoi. The islands had been held by the US-backed South Vietnamese regime. [...] The two countries are locked in long-standing territorial disputes over the Paracel and Spratly islands, which both claim, and often trade diplomatic barbs over oil exploration and fishing rights in the contested waters. [...] Activists waved banners and shouted "Hoang Sa [Paracels], Truong Sa [Spratlys] belong to Vietnam!" before hundreds of uniformed and plainclothes police forced them to leave the area.