Top US military commander Admiral Mike Mullen said Wednesday he was "dismayed" by China's lack of support for efforts to pressure North Korea over the fatal sinking of a South Korean warship.

Mullen, speaking at a dinner of the Asia Society, said that the United States welcomed a stronger leadership role in the region by China, including over the warship sinking which South Korea has blamed on the North.

"I've been encouraged by public statements made recently by Chinese leadership as to the seriousness of this incident and the need for accountability and yet dismayed by a fairly tepid response to calls by the international community for support," Mullen said.

South Korea concluded on May 20 that a North Korean submarine fired a heavy torpedo that sank the Cheonan, killing 46 sailors in one of the deadliest incidents since the 1950-53 Korean War.

China, the North's neighbor and main ally, has expressed condolences but not joined international condemnation of Pyongyang, instead calling for restraint.

Mullen indicated that the United States would soon move ahead with joint exercises with South Korea, which were previously scheduled to take place in early June but were delayed to allow time for diplomacy on North Korea.

"We in the United States military stand firmly by our allies in the Republic of Korea and will move forward, in keeping with international agreements, to demonstrate that solidarity in coming weeks," Mullen said.

"I think it's of no surprise to anyone that we are planning maritime exercises to sharpen skills and strengthen collective defenses," he said.

"I would offer that South Korea's neighbors and friends can assist as well in whatever manner best suits their sovereign needs," he said.