The number of Vietnamese people living in the United States as legal, permanent residents prior to 1975 was quite small - with many during the war being diplomatic staff, military personnel undergoing training, and students. Only after the war did the United States receive a significant number of Vietnamese residents, accepting them in as refugees.

The sheer minuscule number of Vietnamese residents in the United States precluded any attempts at communist agent infiltration, as nearly all Vietnamese in the United States during the war would be either working directly for the Saigon government or be carefully screened as they applied for their visas.

As for Vietnamese terrorism in general, the National Liberation Front's primary goals would not have been served by committing terrorist attacks against the US civilian population; they primarily aimed to collapse domestic Vietnamese popular support for the Saigon regime.

However, following the conclusion of the war, there were a number of active Vietnamese diaspora terrorist organizations, all largely aimed at stoking an insurgency within newly reunified Vietnam, which also arguably committed acts of terror within the United States. The most prominent was the National United Front for the Freedom of Vietnam, which sent several hundred fighters to Vietnam and was responsible for the murder of several Vietnamese-Americans. This group and other like-minded groups were obviously unsuccessful, though they remain active as political organizations agitating for political freedom in present-day Vietnam.

Fox Butterfield. "Vietnamese Anti-Communist Groups Gain Members in U.S." The New York Times, January 7, 1985.

David DeVoss. "A Long Way From Home: Some Vietnamese Immigrants Have Quietly Assimilated; for Others Who Yearn to Return Home, the War Goes On." Los Angeles Times, January 5, 1986.