History of Vietnam since 1945 unstable as no government could keep power for long. There were more coups, often more than one every year. The Communist-run Viet Cong expanded their operation and scored some significant military victories during this period. In 1965, US President Lyndon Johnson sent troops to South Vietnam to secure the country and started to bomb North Vietnam, assuming that if South Vietnam fell to the Communists, other countries in the Southeast Asia would follow, in accordance with the domino theory. Other US allies, such as Australia, New Zealand, South Korea, Thailand, the Philippines, and Taiwan also sent troops to South Vietnam.
Personnel Armor System for Ground Troops Personnel Armor System for Ground Troops Personnel Armor System for Ground Troops (PASGT, pronounced ) is a combat helmet and ballistic vest that was used by the United States military from the early 1980s until the mid-2000s, when the helmet and vest were succeeded by the Lightweight Helmet (LWH), Modular Integrated Communications Helmet (MICH), and Interceptor Body Armor (IBA) respectively. Designed in the mid-1970s as a replacement for the M1 helmet and previous fragmentation vests, prototypes of the PASGT were tested in the late 1970s before being fielded in the early 1980s. In the early 2000s, the PASGT vest was