main Lao political factions (Pathet Lao, neutralist, and pro-Western) agreed to form a second coalition government led by Souvanna Phouma. The coalition government took power in 1962.

During the next two years Souvanna Phouma’s government came under increasing pressure from both the left and the right. Consequently, the neutralists themselves split, left-wing ministers left the government, and by 1965 the country had returned to civil war. As the war in Vietnam escalated, Laos became increasingly important to both North Vietnam and the United States. Both sides violated the neutrality of Laos: the North Vietnamese by infiltrating troops and supplies down the so-called Ho Chi Minh Trail through eastern and southern Laos; and the United States by secretly bombing the trail and by recruiting, financing, and training a mercenary forceof Hmong tribesmen to fight the Pathet Lao in northern Laos. As the war dragged on, the bombing of Laos became heavier and the Hmong "secret army" sustained terrible casualties and had to be reinforced by Thai mercenaries. Both North Vietnamese and Pathet Lao forces also suffered terrible losses.

As the United States sought a way to end the Vietnam War, the Pathet Lao strengthened their position in Laos and negotiations began for a cease-fire. Early in 1973 the Lao political factions agreed to a cease-fire and, in April 1974, formed a third coalition government, this time with equal representation from the right and left. Soon, however, the Pathet Lao gained political dominance. After Cambodia and South Vietnam fell to Communist forces in April 1975, the Pathet Lao used