America's top military officer says he is worried about what he sees as a shift in the focus of China's military buildup, away from developing its ground forces and toward expanding its sea and air power.
Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, told soldiers at an American base in South Korea that China has made a "fairly significant investment" in equipment such as satellites, aircraft, anti-ship missiles and a planned aircraft carrier group.
He said he has moved from being "curious about what they're doing to being concerned about what they're doing."
Mullen added that every country has the right to develop its armed forces, but he would like to have a conversation with China about its intentions. He said it was important to restore military-to-military contacts with China so those talks can take place.
China cut off the military contacts in January to protest a $6.4 billion arms sale to Taiwan.
Mullen is part of a high-level U.S. military and civilian delegation accompanying Secretary of State Hillary Clinton and Defense Secretary Robert Gates on a visit to South Korea. Clinton announced new sanctions against North Korea in Seoul on Wednesday.
All three American officials are engaged in talks with their South Korean counterparts about a series of air and naval exercises to take place in the coming months in the Yellow Sea and Sea of Japan.
The exercises are designed as a response to the sinking in March of a South Korean warship, the Cheonan. An international investigation found strong evidence that the ship was sunk by a North Korean torpedo.
Some information for this report was provided by AFP.