Involved in various political actions, such as protesting against Eisenhower's visit to Italy or fighting against Italian Communist Party members, he already maintained close international links, notably with the Austrian Konrad Windisch, leader of the neo-Nazi Kameradschaftsring Nationaler Jugendverbände (KNJ).

[6] In May 1974, Delle Chiaie’s last known forwarding address was discovered by investigators from the Portuguese Armed Forces Movement when they raided the Lisbon HQ of Aginter Press and its political wing, "Order and Tradition."

Delle Chiaie was arrested in Caracas, Venezuela on 27 March 1987 and extradited to Italy to stand trial for his role in the Strage di Piazza Fontana bombing of Milan on 12 December 1969, when 17 people were killed and 88 wounded.

He was then present at the Ezeiza massacre in Argentina on 20 June 1973,[14] and then met with US-born DINA agent Michael Townley in 1975 to prepare Chilean Christian Democrat Bernardo Leighton's failed assassination.

In South America, he took part in the 'Cocaine Coup' of Luis García Meza Tejada, when a notoriously corrupt military regime forced its way to power in Bolivia in 1980, with assistance from the Argentine SIDE which had been called on for 70 foreign agents.

[15]Judge Baltazar Garzón's investigations demonstrated that he had worked both for Pinochet's political police, the DINA, for the Argentine Anticommunist Alliance (Triple A) and for Hugo Banzer's dictatorship in Bolivia.

[14] According to Le Monde diplomatique, Delle Chiaie met with Abdullah Çatlı in Latin America and during a visit of the Turkish "Grey Wolves" member in Miami in September 1982.

Abdullah Çatlı "is reckoned to have been one of the main perpetrators of underground operations carried out by the Turkish branch of the Gladio organisation and had played a key role in the bloody events of the period 1976-80 which paved the way for the military coup d'état of September 1980.

According to CIA documents, in Madrid, Delle Chiaie also met with Michael Townley, a DINA agent, and Virgilio Paz Romero, a Cuban based in Miami, with connections in Chile, to prepare, with the help of Franco's secret police, the murder of Bernardo Leighton, a Chilean Christian Democrat.

[18] Delle Chiaie, along with fellow neo-fascist Vincenzo Vinciguerra, also testified in Rome in December 1995 before judge María Servini de Cubría that Enrique Arancibia Clavel (a former Chilean secret police agent prosecuted for crimes against humanity in 2004[19]) and Michael Townley were directly involved in the Carlos Prats assassination.

[20] Michael Townley has claimed that DINA agent Enrique Arancibia Clavel, convicted in Argentina for the 1974 assassination of General Carlos Prats, had travelled to California in the autumn of 1977 on banking business for ALFA, alias Stefano Delle Chiaie.