The flagship of the US Navy's Pacific fleet was set to dock in Shanghai on Tuesday for a visit that reflects warming ties between the American and Chinese militaries, as worries mount over North Korea's military ambitions.

The amphibious command and control ship USS Blue Ridge was due at the city's downtown wharf along the Huangpu River, with plans for exchanges between the two navies, and sightseeing and cultural activities for its crew of 1,000 sailors and Marines, the U.S. Consulate in Shanghai said.

An Air Force B-2 bomber along with other aircrafts from the Air Force, Navy and Marine Corps fly over the Kitty Hawk, Ronald Reagan and Abraham Lincoln Carrier Strike groups during the photo portion of Exercise Valiant Shield 2006 over the Philippine Sea, June 18, 2006. Valiant Shield focuses on integrated joint training among US military forces, enabling real-world proficiency in sustaining joint forces and in detecting, locating, tracking and engaging units at sea, in the air, on land and cyberspace in response to a range of mission areas. [Reuters]

The visit follows the attendance at U.S. war games in the Pacific Ocean last week of a 10-member Chinese delegation, including three top-ranking officers - the first-ever such exchange.

The top U.S. commander in the Pacific, Adm. William J. Fallon, has sought to revive military-to-military ties that languished after a 2001 collision between a U.S. spy plane and Chinese jet fighter.

The Blue Ridge last visited Shanghai in February 2004.

The ship, based in Yokosuka, Japan, carries a massive communications system to support the Seventh Fleet and U.S. naval forces in the Asia-Pacific region.

Its visit came as South Korea's foreign minister, Ban Ki-moon, was in Beijing seeking China's help in halting North Korea's apparent plans to test a long-range missile.

Intelligence reports have said the North may be preparing a Taepodong-2, one of its most advanced missiles, at a launch site on the country's northeastern coast. The missile is believed to be capable of reaching parts of the United States.

North Korea's neighbors and Washington have urged Pyongyang to heed warnings not to test the ballistic missile.

After the "Valiant Shield" war games wound down last week near Guam, Pentagon officials said the guided missile cruisers USS Curtis Wilbur and the USS Fitzgerald were being deployed off the Korean coast to monitor the situation.

U.S. officials emphasized that the exercises were not held in response to the North Korean activity or directed at any one nation, but said they were a demonstration of the United States' capabilities should a crisis arise.