AS the United States pursues its uneasy relationship with Nicaragua, there is sometimes debate about whether the Sandinistas were always closet Marxist-Leninists or whether they were nudged into the politics of the left by the policies of Washington. The debate is largely academic.
As a perceptive observer of Nicaragua makes clear in a new book, ``the leaders of the Sandinista Front intended to establish a Leninist system from the day they marched into Managua, whether they called it that or not.''
The observer is Shirley Christian, now a reporter for the New York Times, but who earlier worked in many countries in Latin America for the Associated Press and the Miami Herald.
She won the Pulitzer Prize for international reporting for her coverage of Central America, as well as the George Polk Award for the best foreign reporting in perilous circumstances.
Her book, ``Nicaragua, Revolution in the Family,'' is an eyewitness account of the fall of Somoza and the rise of the Sandinistas. While she had little time for the excesses of Somoza, her clear-eyed reporting of what makes the Sandinistas tick is useful reading for anyone who seeks to understand that successor regime.
By laying fact upon fact, Miss Christian effectively scotches the theory that the Sandinistas were unwilling converts to radicalism. As she shows, the foundation for American attitudes toward the Sandinistas was laid by President Carter, before Ronald Reagan was even nominated.
Meanwhile, as soon as the Sandinistas took control, they embraced their friends in the Marxist world. Foremost among these were the Cubans who, for years before the Sandinistas won power, had given them military training, advice, and supplies. That support, Miss Christian points out, carried with it the obligation to assist other guerrilla organizations.
Once in power, the Sandinistas turned quickly to Moscow, first accepting Bulgarian economic advisers, then seeking arms from the Soviets, ``offering themselves meekly to the Soviets in exchange for more and more weaponry.'' In a sense, she argues, they sold themselves for the means to stay in power in the face of failed policies and widespread unhappiness. But these ties were also the result of the Sandinistas' ``belief in their own principles, the ideological convictions that they themselves held, and for which they were willing to risk the wrath of the United States.''
In the uncertain early days of their rule, the Sandinistas went through the charade of trying to work with other political groups and parties which had been opposed to Somoza.
But their covert intent soon became overt. Daniel Ortega's brother, Humberto, who ran the Sandinistas military operation, told his officers in l98l: ``Our revolution has a profoundly anti-imperialist character, profoundly revolutionary, profoundly classist: We are anti-Yankee, we are against the bourgeoisie, we are inspired by the historic traditions of our people, we are inspired by sandinismo, which is the most beautiful tradition of this people, developed by Carlos Fonseca, we are guided by the scien tific doctrine of the revolution, by Marxism-Leninism.''
He went on to instruct his military officers: ``Without sandinismo we cannot be Marxist-Leninists, and sandinismo without Marxism-Leninism cannot be revolutionary. For that reason they are indissolubly united and for that reason our moral force is sandinismo, our political force is sandinismo, and our doctrine is Marxism-Leninism.''
Although the more controversial parts were deleted when the speech was later circulated by the government, the theme left then -- and still leaves today -- no doubt about the ideological motivation and goals of the Sandinista regime in Managua.
John Hughes is a Pulitzer Prize-winning journalist who was assistant secretary of state from 1982 to 1984.