"In 1964, due to the Cyprus crisis, Greece withdrew military units from NATO forces in the Southern Mediterranean, over threats of invasion of Cyprus by fellow NATO member Turkey.[8] Later in 1974 due to the invasion of Cyprus by Turkish forces, Greece withdrew from NATO military command. Notwithstanding, the country did not withdraw entirely from the organisation, but became significantly less active.[9]

In 1980, the Greek foreign minister Konstantinos Mitsotakis made remarks about the situation where he could see Greece fully withdrawing from the organisation. However, later diplomatic pressure from the United States led to Greece fully re-integrating with the alliance.[10]"

https://en.wikipedia.org/wiki/Withdrawal_from_NATO#Greece