By Steve Jones, About.com Guide

United States Secretary of Defense Leon Panetta visited Hanoi, Vietnam, June 4, 2012, as part of a trip through Southeast Asia to help the United States reorient its foreign policy toward the Asia Pacific region instead of the Middle East. Forty years ago, with the Vietnam War still six months from ending, such a trip would have been unthinkable. No doubt many a Vietnam veteran finds it hard to believe that the U.S. and Vietnam have had normalized relations for 17 years.
In fact, the country that is so synonymous with American military bungling and social upheaval now plays host to more than 400,000 U.S. tourists yearly.
Era Of Bad Relations And War
American military involvement in Vietnam began with World War II. Before the war, Vietnam was a French colony. In 1941, however, Japan took over the country. During the war, the United States teamed with Vietnam, China, and the United Kingdom to throw Imperial Japan out of Southeast Asia.
But at the war's end, victorious European allies allowed France to retake Vietnam as an imperial possession. Vietnamese nationalists, led by Ho Chi Minh, had hoped that World War II would mark the end of Vietnamese colonialism, and they opposed the French return. (Ho Chi Minh had styled himself a revolutionary leader of Vietnam comparable to America's George Washington; he even hoped to have an American-style "declaration of independence" and a July 4 independence day.)
The United States, which became de facto Western leader after World War II, could not abide Ho Chi Minh's revolutionary movement because he had ties to both Communist Russia and China. Instead, the U.S. backed the French return. In 1954, however, Ho Chi Minh and his military leader Vo Nguyen Giap embarrassed the French at the siege of Dienbienphu and forced them to give up the country.
Instead of allowing the communist Ho Chi Minh and his followers to take control of the country, the U.S. stepped into the power vacuum created when France left. As a compromise, the U.S. partitioned the country at the 17th Parallel (close to the thin geographic neck of the country) and allowed Ho and the Communists to govern North Vietnam from Hanoi. A U.S.-backed "democratic" government ran South Vietnam from Saigon. When the U.S. reneged on a promise to allow free elections in 1956 to determine the unification of Vietnam, Ho Chi Minh began resistance against the United States.
The U.S. actively fought North Vietnamese and Viet Cong (South Vietnamese who fought for the Communists) from 1965 to 1973 when it ceased military action. In April 1975, North Vietnamese troops rolled across the south, united the country under a communist government. They changed the name of Saigon to Ho Chi Minh City in honor of the leader who had died in 1969.
Era Of Good Relations
While Vietnam remains "communist," free market forces drive it more now than Marxist ideology. This statement from the U.S. State Department sums it up nicely: " Though Vietnam remains a one-party state, adherence to ideological orthodoxy has become less important than economic development as a national priority."
In July 1995, U.S. President Bill Clinton formally normalized diplomatic relations with Vietnam. They exchanged ambassadors, and the U.S. has consulates in Ho Chi Minh City and Danang, both of which were U.S. bases in the war.
Other elements of U.S.-Vietnamese cooperation include:

• U.S.-Vietnam Bilateral Trade Agreement, 2001, which has facilitated trade between the two countries. U.S. exports to Vietnam in 2010 totaled $3.7 billion; imports from Vietnam were $14.9 billion.

• Foreign Direct Investment from U.S. private investors equaled $9.8 billion.

• Bilateral Air Transport Agreement, 2003, amended 2008, enables direct passenger flights between the U.S. and Vietnam, as well as cargo flights.

• Unexploded ordinance location and clearing: the U.S. State Department has committed $62 million over two decades to finding and removing unexploded munitions from the Vietnam War.

Search For MIAs
During Panetta's visit, Vietnam announced that it was opening three new areas in which to search for the remains of American soldiers listed as Missing In Action (MIA). The State Department reports that 1,288 soldiers remain unaccounted for in Vietnam. Four times each year, a Joint POW/MIA Accounting Command (JPAC) conducts searches to account for the missing personnel.