George K. Tanham, 81, a researcher, former government worker and retired RAND official who served as vice president in charge of the research organization's Washington office from 1970 to 1982, died of congestive heart failure March 29 at the Hospice of Northern Virginia. He lived in Washington.

Dr. Tanham, an authority on South and Southeast Asia and national security issues, joined RAND as a consultant in California in 1954 and became a full-time employee in 1955. He transferred to Washington in 1957, became a deputy vice president in 1965, a vice president and trustee in 1970, and vice president for its Air Force division. He also was a senior researcher and resident consultant before his retirement in 1987.

He took leave from RAND to serve with the Agency for International Development as its associate director for counterinsurgency in South Vietnam in 1964 and 1965. From 1968 to 1970, he held the rank of minister while serving as special assistant for counterinsurgency to the ambassador to Thailand.

Dr. Tanham, who served as editor in chief of the journal Studies in Conflict and Terrorism, was the author of the 1961 book "Communist Revolutionary Warfare: The Vietminh in Indochina," one of the first English-language books on the subject and an outgrowth of study he had done in Europe and Vietnam.

He also was a co-author of the 1966 book, "War Without Guns: American Civilians in Rural Vietnam," and a 1974 book based on his years in Thailand, "Trial in Thailand." He was co-author of the 1989 book "Who Will Win? A Key to the Puzzle of Revolutionary War." He also contributed to the recent "Securing India: Strategic Thought and Practice" and was co-author of "Indian Air Force: Trends and Prospects."

Dr. Tanham, a Tenafly, N.J., native and a Princeton University graduate, received a doctorate in history and political science from Stanford University. During World War II, he served in Europe as an artillery officer with the Army's 7th Armored Division. His honors included two Silver Stars, a Purple Heart and an Air Medal.

Before joining RAND, he taught military history at the California Institute of Technology.

His marriage to Patricia Tanham ended in divorce. His second wife, Barbara, died in 1987.

Survivors include his wife, Kathleen of Washington; three children from his first marriage, George Jr., of Phoenix, Geoff F. Tanham of Hopkinton, Mass., and Alexis T. Doering of Scottsdale, Ariz.; four children from his second marriage, Barbara T. Sampora of Purcellville, Maedi T. Carney of Washington, Ruth T. Marshall of Round Hill, Va., and P. Ramsay Tanham of Arlington; and 14 grandchildren.