Illia was invited in 1975 to a diplomatic mission to the Soviet Union; he declined and proposed instead. Upon his return, Alfonsín became one of the founding members of the Permanent Assembly for Human Rights. He served as the defense lawyer for Mario Roberto Santucho, leader of the ERP guerrillas, but only to carry out due process of law, and not because of a genuine desire to support him. The 1976 Argentine coup d'état against President Isabel Martínez de Perón started the National Reorganization Process. Alfonsín filed several "Habeas corpus" motions, requesting the freedom of victims of forced disappearances. He also visited other countries, denouncing those disappearances and violations of human rights. He established the magazine "Propuesta y control" in 1976, one of the few magazines that criticized the military dictatorship during its early stages. The magazine was published up to 1978. His editorials were collected in 1980 in the book "La cuestión argentina". He expressed opposition to the 1982 Falklands War, criticizing the deployment of troops by both sides during the conflict. The Argentine defeat in the war marked the decline of the military dictatorship. The main political parties united in the "Multipartidaria", issuing a joint request to the dictatorship to call for elections. Alfonsín proposed the appointment of Arturo Illia as the head of state of a transition government, similar to the Metapolitefsi in Greece. The Movement for Renewal and Change took control of the UCR; Balbín had died the previous year.