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 1830. Since then, the two countries have faced each other in four major wars—the Greco-Turkish War (1897), the First Balkan War (1912-1913), the First World War (1914-1918), including the Greek genocide (1913-1922), and finally the Greco-Turkish War (1919–22), which were 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 after the 1950s due to the 1955 Istanbul pogrom, the Cyprus issue, and the expulsion of the Istanbul Greeks in the 1960s, the 1974 Cypriot coup d'etat, immediately followed by the Turkish invasion of Cyprus in 1974, the &lt;a href="Imia/Kardak"&gt;Imia/Kardak&lt;/a&gt; military crisis in 1996 and subsequent military confrontations over the Aegean dispute. A period of relative normalization began after 1999 with the so-called "earthquake diplomacy", which notably led to a change in the previously firmly negative stance of the Greek government on the issue of the accession of Turkey to the European Union. As of 2021, military tensions have risen again due to conflicts over maritime zones in the Aegean and Eastern Mediterranean.