The most highly-publicized instrusion into the United States of Chile's Directorate of National intelligence (DINA) grew out of the assassination of Orlando Letelier, former Chilean ambassador to the United States, in September 1976.

The indictment of the director of Chile's intelligence service, Manuel Couteras Sepulveda, by a federal grand jury in Washington provided a remarkable case study of foreign espionage operations aimed at silencing political dissidents within the United States.

Letelier's assassination fit into a pattern of reprisal practiced not only by DINA but also by a wider network of Latin American intelligence agencies comprising Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay, according to the Senate report and independent testimony of U.S. intelligence officials. The joint effort is known as Operation Condor.

The Senate report mentions a "phase three" aspect of Operation Condor which involves the formation of special teams to carry out "sanctions" - including assassinations - against the enemies of its constituent governments.

One such operation was targeted in 1974 against a group of European leftists, including the notorious terrorist known as Carlos. In this case the CIA learned of the plans and warned the governments of France and Portugal, where the assassinations were expected to be carried out, according to intelligence officials. The plan was called off when the governments of those two countries warned representatives of Condor against carrying it out.

The Senate report disclosed that Condor had considered establishing its own station in Miami in 1974. When the CIA learned of this scheme, too, it alerted the State Department.

Secretary State Henry Kissinger rejected a State Department proposal to protest formally to the to the governments involved in Condor. Instead it was decided that the CIA would express U.S. disapproval through regular intelligence channels, by informing DINA. No Condor station was opened in Miami.

The Senate report said the FBI had concluded early in its investigation of the Letelier assassination that the murder "may have been carried out as a third phase of Operation Condor." CAPTION: Picture, ORLANDO LETELIER...assassinated in 1976