Greek–Turkish relations regime, there were periodic crises with Turkey, which suspected that the Greek regime was planning a pro-unification coup in Cyprus. A 1971 Turkish law nationalized religious high schools, and closed the Halki seminary on Istanbul's Heybeli Island which had trained Greek Orthodox clergy since 1844. On July 15, 1974, a band of Greek Cypriot nationalists formed EOKA B, advocating Enosis (Union) with Greece and, backed by the Greek military junta in Athens, staged a coup against the Cypriot President and Archbishop Makarios. An ex-EOKA man, Nikos Sampson was appointed President. On July 20, Turkey—using its guarantor status arising from the
Accession of Turkey to the European Union in the European Union. The former Greek Prime Minister Kostas Karamanlis stated that Turkish membership of the EU could only be predicated upon, "full compliance, full accession" in December 2006. In 2005 the European Commission referred to relations between Turkey and Greece as "continuing to develop positively" while also citing a key barrier to progress being Turkey's ongoing claim of "casus belli" over a dispute about territorial waters boundaries. In September 2017, Greek Prime Minister, Alexis Tsipras, mentioned that halting accession talks with Turkey would be a strategic mistake by the European Union, amid a war of words raging between