Other issues dividing Greece and Turkey involve the delimitation of the continental shelf in the Aegean Sea, territorial waters and airspace. In March 1987 a dispute concerning oil drilling rights, almost led to war between the countries with Greece advocating the dispute to be decided by the International Court of Justice. In early 1988, the Turkish and Greek Prime Ministers met at Davos, Switzerland, and later in Brussels. They agreed on various measures to reduce bilateral tensions and to encourage cooperation.