The relations between the Greek and the Turkish states have been marked by alternating periods of mutual hostility and reconciliation ever since Greece won its independence from the Ottoman Empire in 1832. Since then the two countries have faced each other in four major wars—the Greco-Turkish War (1897), the First Balkan War of 1912 to 1913, the First World War (1914 to 1918) and finally the Greco-Turkish War (1919–22). The latter was followed by the Greco-Turkish population exchange and a period of friendly relations in the 1930s and 1940s. Both countries entered NATO in 1952. Relations deteriorated again in the 1950s due to the Cyprus issue, the 1955 Istanbul pogrom and the expulsion of the Istanbul Greeks in the 1960s, the Turkish invasion of Cyprus in 1974, and subsequent military conf