Vietnam
COUNTRY DESCRIPTION: Vietnam is a developing, mainly agrarian country in the process of moving from a centrally planned to a market economy. Political control rests in the Communist Party. Tourist facilities are not well established, but are improving in certain areas, especially in Hanoi, Ho Chi Minh City, and some beach and mountain resorts. Read the Department of State Background Notes n Vietnam for additional information.
ENTRY/EXIT REQUIREMENTS: A valid passport and Vietnamese visa are required. A visa must be obtained from a Vietnamese Embassy or Consulate prior to traveling to Vietnam; entry visas are not available upon arrival. Americans arriving without an appropriate Vietnamese visa will not be permitted to enter, and will be subject to immediate deportation. Vietnamese visas are usually valid for only one entry. Persons planning to leave Vietnam and re-enter from another country should be sure to obtain a visa allowing multiple entries. See our Foreign Entry Requirements brochure for more information on Vietnam and other countries. Visit the Embassy of Vietnam web site for the most current visa information.
Even while in possession of a valid visa, some travelers have been refused entry to Vietnam. U.S. citizens are cautioned that Vietnamese immigration regulations require foreigners entering Vietnam to undertake only the activity for which their visas were issued. Change of purpose of your visit, requires permission from the appropriate Vietnamese authority in advance. U.S. citizens whose stated purpose of travel was tourism, but who engaged in religious proselytizing have had religious materials confiscated and have been expelled from Vietnam. An American whose U.S. passport is lost or stolen in Vietnam must obtain both a replacement passport and a replacement Vietnamese visa. The U.S. Embassy and Consulate General can issue limited validity emergency replacement passports in as little as one day, but the Vietnamese government requires three working days, not to include the day of application, to issue a replacement visa. Neither the U.S. Embassy nor the Consulate General can expedite replacement Vietnamese visas.
Source