Chinese Vice President Xi Jinping began the last day of his U.S. visit by urging closer ties and arguing that Americans benefit from their trade relationship with China. "A prosperous and stable China will not be a threat to any country," Xi said Friday. "It will only be a positive force for world peace and development." Xi, who is expected to become president of the world's most populous nation next year, started his fourth day in the United States at a downtown Los Angeles trade conference hosted by the Chinese Ministry of Commerce. His American counterpart, Vice President Joe Biden, joined him later. California Gov. Jerry Brown and Los Angeles Mayor Antonio Villaraigosa both lauded the U.S.-China relationship, according to a report of the Associated Press.