The Aegean Crisis of March 1987 was a political and military standoff between Turkey and Greece over offshore oil exploration near the Greek island of Thasos in the Aegean Sea. The crisis was driven by conflicting claims over the Aegean Sea's continental shelf.
The crisis was triggered when Canadian firm Denison Mines, a member of an international oil consortium, announced plans to drill east of Thasos. The location was beyond Greece's territorial sea, but within waters claimed by Athens and disputed by Ankara. To prevent the operation, the Greek government sought to acquire a controlling share in the oil consortium. However, the Turkish government misread this intervention as an indication that the Greek government was preparing to initiate its own offshore drilling project in the disputed waters. Following a request for clarification, a miscommunication occurred between the Greek deputy foreign minister and the Turkish ambassador. In response, Turkey dispatched a survey vessel to the area with an escort of two Turkish warships. Both nations placed their military forces on high alert. The tension was amplified by the absence of a direct channel of communication between the two governments. The crisis reached its peak when the Turkish government decided to dispatch another survey vessel, escorted by two more warships, while the Turkish prime minister was on a flight and unaware of the decision. The situation raised concerns within the North Atlantic Treaty Organization (NATO) as both countries were members of the alliance.
Diplomats intervened and resolved the misunderstanding. Turkey withdrew its naval vessels under the condition that Greece would not seek oil drilling in the north Aegean Sea beyond its territorial waters. A diplomatic rapprochement followed with a meeting between the prime ministers Andreas Papandreou and Turgut Özal in Davos the following year. The meeting launched the Davos process, aimed at easing tensions in GreekTurkish relations. However, political opposition in both countries diminished the progress achieved in Davos.
Background
The 1987 Aegean Crisis stemmed from a series of incidents and tensions that developed during the 1970s over sovereign rights to the continental shelf in the Aegean Sea. These tensions became apparent during the negotiations for the United Nations Convention on the Law of the Sea (UNCLOS) that started in 1973. One of the emerging outcomes was UNCLOS to grant participating states the right to extend their territorial waters from six to twelve miles from their coastlines, including around their islands. If this were to occur, Turkish ports in the Aegean and Black Sea would access the high seas only through waters under Greek sovereignty and jurisdiction. Turkish officials described this potential outcome as turning the Aegean Sea into a "Greek lake". Turkey declared, beginning in 1974 and on several occasions thereafter, that any such extension of Greece's territorial waters would constitute a casus belli (cause for war). Greece refrained from extending its territorial waters in the Aegean Sea while retaining the right to do so at a later date.
The Cyprus crisis of 1974 was a turning point in Greek–Turkish relations. At the time, Cyprus was a republic, following a British colonial rule, under the Treaty of Guarantee (1960), which was an agreement between the British, Greek, and Turkish governments. The majority of the Greek Cypriot population sought enosis (union) with Greece. However, previous Greek governments had been skeptical because of the Turkish minority and assertiveness of Turkey. At the time, Cypriot President Makarios III had abandoned enosis after the republic's creation. This position brought him into conflict with the Greek junta that came to power in Greece in 1967. The junta, which was dominated by military officers who favored enosis, viewed Makarios as an obstacle. In July 1974, the junta supported a coup by the Cyprus National Guard in an unsuccessful attempt to remove Makarios. The attempt amplified the political crisis, further exacerbating friction between the Greek and Turkish Cypriot communities. Turkey intervened militarily, citing the protection of the Turkish Cypriot community and its role as a guarantor power under the 1960 treaty. Turkish forces subsequently occupied approximately the northern third of the island, resulting in the displacement of the Greek Cypriot population and the island's division. The Turkish invasion crystallized Greek perceptions of Turkish military intentions and became a source of tension between Athens and Ankara, contributing to the deterioration of bilateral relations.
The Turkish invasion of Cyprus led to the fall of the junta and the return of the Greek political government. The new Greek government strengthened the military presence on several eastern Aegean islands. Turkey accused Greece of violating the islands' demilitarized status under previous agreements and established the Aegean Army in Izmir in 1975, with amphibious capabilities that further heightened Greek concerns about Turkish intentions. Successive Greek governments maintained that Samothrace and Lemnos had been relieved of their demilitarized status by the Montreux Convention of 1936, while the militarization of other eastern Aegean islands was justified as a response to the presence of the Aegean Army.
Tensions between the two countries escalated during the 1976 Aegean Crisis. Driven by acute supply pressures from the 1973 oil crisis, the Turkish government sought to expand its hydrocarbon exploration in the Aegean Sea. Meanwhile, Greek officials made exaggerated claims in 1973 about significant oil reserves discovery near Thasos and Lemnos, leading Turkish policymakers to suspect Greece was trying to monopolize the region's oil resources. In August 1976, Ankara dispatched a seismic survey vessel, escorted by a warship, west of the Greek island of Lesbos. The vessel conducted seismological surveys in Turkish territorial waters and in disputed areas of the continental shelf under the high seas. Tensions escalated when the head of the Turkish Nationalist Movement Party claimed that the eastern Aegean islands should have been Turkish. This prompted Greek statements that a forceful response would be forthcoming and that the Greek army was on full alert, bringing the two countries to the brink of war. Subsequently, the Greek government appealed to the UN Security Council (UNSC) and International Court of Justice (ICJ), seeking to defuse the crisis through diplomatic efforts. While the UNSC recommended restraint, the ICJ declared that it lacked jurisdiction to rule on the Aegean continental shelf dispute. Later that year, the two sides signed the Bern Agreement, which froze unilateral exploration activities. However, mutual suspicion persisted. Additionally, after 1978, the two sides had no direct communication between their leaders until after the 1987 crisis.
Events Prelude In 1981, Andreas Papandreou became prime minister of Greece. His government considered the November 1976 Bern Agreement's drilling ban east of Thasos void, since Aegean talks had stalled. However, his government was also entangled in legal disputes in an attempt to control oil companies that wanted to expand exploration beyond Greek territorial waters. The predominant Greek view at the time was that most of the Aegean continental shelf was Greek and so oil companies had to seek permission from the Greek state. Given these circumstances, exploration and extraction of oil beyond Greek territorial waters was improbable.
In the 1983 parliamentary election, Turgut Özal and his party won 45.14% of the vote, enabling him to form a single-party government and become prime minister of Turkey. The outcome was unexpected because the Turkish military, which had its own candidate, did not support Özal, and a single-party government was also uncommon. For Özal, improving relations with Greece became a top priority of Turkish foreign policy, as he viewed it as a prerequisite for closer ties with the European Community. Toward this goal, he introduced several measures to improve relations with Greece between 1984 and 1986. These included abolishing entry visas for Greek citizens and improving conditions for the Greek minority in Istanbul. He also took initiatives to strengthen trade between the two countries. Despite these overtures, little progress was achieved between the two leaders. Papandreou continued the policy of isolating Turkey in international forums, including its attempt at an association agreement with the EC. The lack of progress led the Turkish military-diplomatic establishment to call for an end to the policy of tolerance toward Greece.
Miscommunication Tensions started to rise on 19 February 1987, when the Greek government announced plans to purchase majority shares in foreign companies drilling near Thasos, citing the strategic value of this area. It was followed by an announcement by Denison Mines, a Canadian company, of plans to drill eight to ten miles east of Thasos. Although the proposed drilling site was beyond Greece's six-mile territorial sea, it fell within the twelve-mile limit claimed by Greece, angering the Greek government. The Greek government faced a dilemma: allow exploration and risk a crisis with Turkey, or expropriate the company and take control itself. Although the Greek officials believed it had a strong legal case, it feared a compromise ruling by the courts. Intelligence gathered by Greece in late 1986 also suggested that Turkey was planning to provoke a crisis to force Greece into bilateral negotiations. Papandreou decided to buy the shares of the company to control its activities. However, the Turkish government viewed the company's public statement and the Greek government's purchase of shares as confirmation of Greece's intention to assert its continental shelf claims by drilling in disputed waters. The Greek actions alarmed the Turkish government, which was at the time seeking membership in the European Economic Community (EEC).
Turkish ambassador sought assurances from Greek Deputy Foreign Minister Yannis Kapsis that the Greek government had no intention of drilling beyond its territorial waters. Kapsis, however, asserted Greece's sovereign right to drill anywhere on its continental shelf, even though this was not the Greek government's immediate plan. Akıman interpreted this as an intent to drill beyond six miles, and Ankara warned that any activity in disputed areas would prompt a Turkish response. The Greek government refused to back down, announcing Aegean military exercises on 19 March. On the same day, the Turkish survey vessel Piri Reis was sent to the area with an escort of two Turkish warships. Both governments placed their military forces on high alert.
Crisis peak