The U.S. Navy ammunition ship Richard E. Byrd sailed into the Vietnamese port in Cam Ranh Bay several weeks ago, the first American warship to dock at that huge base since U.S. forces withdrew from Vietnam in 1973.

The ship was also the first of the USN to respond to a Vietnamese invitation to ships of all nations to call at the base built by the U.S. during the Vietnam War. Byrd remained there for a week as Vietnamese crews cleaned the hull underwater, polished the ship’s propeller, fixed shipboard piping, and overhauled the cooling system.

That an American warship sailed into a port in Vietnam to be repaired by Vietnamese shipyard workers less than 40 years after the end of a brutal war can only be termed remarkable.

In nearly 20 years of hostilities, 58,000 American soldiers, sailors, marines, and aviators were killed. An estimated 266,000 South Vietnamese soldiers and 1.1 million Viet Cong and North Vietnamese fighters lost their lives. Several million Vietnamese civilians died.

Today, the prime motive for this reconciliation can be summed up in one word: China.

The Vietnamese make little effort to hide their fear of China. China occupied much of Vietnam for a thousand years until 1010. For the next 850 years, the Vietnamese fought off Chinese incursions until Vietnam fell under French colonial rule. Vietnamese communists defeated the French at Dien Bien Phu in 1954 to end French rule.

Vietnam’s most recent battle against China was in 1979, when Chinese forces sought “to teach Vietnam a lesson” but got whipped by the Vietnamese who at that time fielded the world’s most experienced army.

For Americans, it has become increasingly evident that China seeks to drive U.S. forces out of Asia. China sees the U.S. as the main obstacle to Beijing’s rule of Asia. To counter the Chinese drive, the US has been cultivating allies, including Vietnam.

A focal point in which the U.S. and Vietnam have a common interest is the South China Sea. China has claimed most of that sea as territorial waters while the U.S., Vietnam, and other Southeast Asian nations have asserted that it is an international waterway.

Keeping it open is vital to the economies of Asia because more shipping passes through that channel each year than through the Suez and Panama Canals combined. For the U.S. Navy, the sealane is crucial for warships transiting between the Pacific and Indian Oceans to preclude the time-consuming and costly need to sail around Australia.

The U.S. and Vietnam began the reconciliation in 1995 when they opened diplomatic relations. At first, contacts were tentative and sporadic, although President Bill Clinton made a three-day visit to Hanoi in 2000.

President George W. Bush went to Hanoi in 2006 to attend an Asia-Pacific Economic Cooperation meeting, a forerunner of a meeting scheduled for Honolulu next month. The following year, President Nguyen Minh Triet made the first visit to Washington by Vietnamese head of state since the war.

Then the amphibious ship Peleliu, reconfigured into a hospital ship, docked at Danang on a medical mission in 2007. In 2008, the hospital ship Mercy ship dropped anchor off Khanh Hoa province on a similar mission. Sen. James Webb, the Virgina Democrat and chairman of the East Asia subcommittee of the Foreign Relations Committee who had fought in Vietnam as a Marine, visited that country again.

In 2009, General Carrol “Howie” Chandler, commander of the Pacific Air Forces (PACAF) with headquarters in Honolulu, was the first Air Force four-star to travel to Vietnam in the postwar period. The aircraft carrier Stennis received Vietnamese military and civilian officials flown out to the ship at sea.

The command ship Blue Ridge and the guided missile destroyer Lassen, commanded by Cdr. H.B. Le, a Vietnamese-American, made port calls. Senator John McCain, Republican of Arizona, met with Prime Minister Nguyen Tan Dung in Hanoi, where the senator as a naval aviator had spent six years as a prisoner of war.

A Vietnamese military delegation made the first visit to PACAF headquarters at Hickam to discuss search and rescue missions. In Pacific Angel, 60 Air National Guard medics flew into Quang Tri Province to treat about 5,000 patients.

Similarly, in Pacific Angel 2010, PACAF medics treated 12,000 patients and renovated two medical clinics. The hospital ship Mercy returned to Vietnam with medics treating 19,000 patients and performing 132 surgical procedures. Engineers renovated a clinic and school for disabled children.

This year, in addition to the port call by the ammunition ship, the carrier George Washington was visited by Vietnamese senior civilian and military officials at sea. Air Force security officers received Vietnamese officers at Andersen AFB on Guam to discuss base security.

Perhaps the most ironic event in this series was the port call in Danang last year by the guided missile destroyer John S. McCain, named for the admiral who commanded U.S.forces in the Pacific during the Vietnam War while his son was a prisoner in Hanoi.