Nicaragua's ties with the United States traditionally have been closer than those of its Central American neighbors. In 1919, the U.S. Marines took over the government to disband the competing local armies that had made Nicaragua their battleground for decades. American forces remained in the country for most of the next 13 years, finally withdrawing in 1933. They left behind a newly formed National Guard, designed to be a truly national force, under the leadership of Gen. Anastasio Somoza Garcia, and an elected civilian government. Although a small guerrilla group, led by dissident military officer Cesar Augusto Sandino, was lodged in the northern hills, its fight had been against the Marines rather than the Nicaraguan government. Upon U.S. disengagement, the guerrillas ceased hostilities.

By 1936, the president had been overthrown and Somoza had installed himself as head of state in addition to commander in chief of the military forces. Sandino had been killed by Somoza's soldiers, and a period of relative tranquility under a family dictatorship that was to last 43 years had begun.

As in most Central American republics, small leftist guerrilla cells had formed in the early 1960s, but were not seen by the Somoza regime as a serious threat. It was not until 1974 that the Sandinista National Liberation Front, named after Sandino in opposition to both the Somozas and the United States, posed a true challenge to the government of then-President Anastasio Somoza Debayle, the second son of Somoza Garcia. Over the next five years, the growing strength of the guerrillas, the disenchantment of the local political and business communities with Somoza and his government's break with the Carter administration, combined to undermine the regime and ultimately led to its overthrow following a brief civil war in 1979.

Although the new government, led by the Sandinista guerrillas, promised a pluralistic democracy and received economic support from Carter, its own increasing authoritarianism and the conservativism of the incoming Reagan administration led to internal strife and strained relations with the United States last year. The administration has charged that the Sandinistas are Marxist totalitarians, tightly tied to Cuba and the Soviet Union, and that they are aiding guerrillas in El Salvador. The Sandinistas have denied aiding the Salvadoran rebels and have countercharged the United States with conspiring to destabilize their government.