Before 1949, he worked for the
Greek diasporic newspaper
National Herald. From 1949 to 1950, he worked in the press office of the
Greek Embassy in
Washington, D.C. In 1950, he joined the
Central Intelligence Agency. with a staff of 24 and a budget of $1.5 million (equivalent to $ million in ). Joannides was charged with managing anti-Castro
propaganda and the disruption of pro-Castro organizations. In that role, he was also known by the
cover names "Howard", "Mr. Howard", and "Walter Newby". Joannides directed and financed the
Directorio Revolucionario Estudantil (DRE), or Student Revolutionary Directorate, a group of anti-Castro
Cuban exiles whose officers had contact with
Lee Harvey Oswald in
New Orleans in the months before the
assassination of President John F. Kennedy on November 22, 1963. Oswald took part in a local radio debate with DRE members, Reporter
Jefferson Morley wrote: "The spy [Joannides] withheld information about his own actions in 1963 from the congressional investigators he was supposed to be assisting. It wasn't until 2001, 38 years after Kennedy's death, that Joannides' support for the Cuban exiles, who clashed with Oswald and monitored him, came to light."
G. Robert Blakey, the Chief Counsel and Staff Director of the HSCA, later said that Joannides "obstructed our investigation" and that if he had known about Joannides' Cuban operations he would have "demanded that the agency take him off the job" and "sat him down and interviewed him. Under oath." According to Dan Hardway, an investigator for the HCSA, Joannides was running a "covert operation" to obstruct their investigation into the assassination. Another HSCA investigator,
Gaeton Fonzi, said of Joannides that "instead of facilitating document requests he was more and more dancing around, delaying and blocking them". The CIA later evaluated Joannides' performance in this role as "outstanding". In July 1981, he was awarded the
Career Intelligence Medal, where his liaison role with the HCSA and his work with the Cuban exiles were cited among a multitude of reasons for the award. In 2013,
John R. Tunheim and Thomas E. Samoluk wrote in the
Boston Herald: {{Blockquote In 2022, the
Mary Ferrell Foundation filed a lawsuit in an attempt to secure the release of the Joannides files. In 2025, government documents revealed that Joannides had contact with the anti-Castro Cuban exile
Directorio Revolucionario Estudiantil (DRE), which confronted Oswald three months before the assassination of John F. Kennedy. The DRE themselves had claimed their CIA contact went by the name "Howard" and these documents revealed that Joannides did in fact go by the
cover name "Howard". Previously the CIA had denied to the
Warren Commission and the House Select Committee on Assassinations (HSCA) that such an individual existed, and in 1998 they told the
Assassinations Records Review Board that "Howard" may have been "nothing more than a routing indicator". ==Personal life and death==