General Peter Pace, the chairman of the Joint Chiefs of Staff, made the statement during a four-day visit to Beijing.
The United States and Japan have recently raised concerns about China's growing military budget, and about the missile test, in which a Chinese missile shot down one of the country's own satellites. But Pace said China's military buildup is not a threat, so long as Beijing communicates its intentions.
"With regard to the military budget, it is not so important what the exact number is," Pace said. "It is important what capacities are being built and why, and what do we understand with each other about how that is being spent."
Pace also said he had assured Chinese leaders that the United States does not support independence for Taiwan, and wants a peaceful resolution to tensions between Taiwan and mainland China.