Chin a said Thursday its army chief of staff would visit the United States in May, as the two countries try to bolster military relations amid their growing rivalry. "The two armies are now faced with new opportunities for development of their relations," defence ministry spokesman Geng Yansheng told reporters as China released a white paper outlining its defence policy. He said Chen Bingde, chief of staff at the People's Liberation Army, would visit the United States in May as part of efforts to strengthen military ties -- a major point of friction in wider Sino-US relations.