The commander of America's Pacific fleet says he respects China's right to manage its interests around the world but worries about erratic behavior by North Korea.

Vice Admiral Scott Swift, Commander of U.S. 7th Fleet, spoke to reporters in Hong Kong Wednesday during a port call by the battle group attached to the giant aircraft carrier USS George Washington.

He acknowledged that China is growing rapidly, both economically and militarily, but said that is not a problem as long as it is prepared to work with other countries.

But he said North Korea is a concern because so little is know about its leaders' intentions.

Rear Admiral J.R. Haley, commander of the George Washington, praised the progress and professionalism of the Chinese navy during a separate meeting with Chinese officials in Hong Kong.

Swift took command in September of the Seventh Fleet, which is based in Japan and covers the Pacific and Indian Oceans. The fleet has about 60 vessels and 40,000 crew members.