US Defense Secretary Robert Gates called on China Thursday to explain its intentions in undertaking a major military buildup that the Pentagon warns is altering the military balance in the region. "There is no question that the Chinese are building significant capacity," Gates said. "Our concern is over their intent." Gates spoke to reporters during a stopover here on his way to Singapore where he was expected to raise US concerns over the increases in Chinese military spending, the size and scope of which is secret. "One of the central themes of everyone who is talking to the Chinese is...