China allowed a blind legal activist, Chen Guangcheng, to leave a hospital in Beijing on Saturday and board a plane bound for the United States, a move that could signal the end of a diplomatic standoff between the two countries. Chen's escape from house arrest in northeastern China last month and subsequent stay in the U.S. embassy caused huge embarrassment for China and led to a diplomatic rift while U.S. Secretary of State Hillary Clinton was visiting Beijing for talks to improve ties between the world's two biggest economies.