In the 1950s and 1960s, Greece developed rapidly, initially with the help of the U.S. Marshall Plans' grants and loans, and later through growth in the tourism sector. In 1967, the Greek military seized power in a coup d'état, overthrew the centre right government of Panagiotis Kanellopoulos and established the Greek military junta of 1967-1974 which became known as the Régime of the Colonels. The Central Intelligence Agency was involved in the coup and President Clinton later apologised for the interference. In 1973, the régime abolished the Greek monarchy. In 1974, dictator Papadopoulos denied help to the U.S. and rumor has it that as a result the U.S., through Kissinger's efforts, initiated a second coup. Colonel Ioannides was appointed as the new head-of-state.

Many hold Ioannides responsible for the coup against President Makarios of Cyprus—the coup seen as the pretext for the first wave of the Turkish invasion of Cyprus in 1974 (see Greco-Turkish relations). The Cyprus events and the outcry following a bloody suppression of Athens Polytechnic uprising in Athens led to the implosion of the military régime. A charismatic exiled politician, Konstantinos Karamanlis, returned from Paris as interim prime minister and later gained re-election for two further terms at the head of the conservative Nea Dimokratia party.