BRUSSELS—The United States, European Union, United Nations, and NATO may soon be confronted with a new reality in the eastern Mediterranean, one characterized by heightened tensions, possible naval incidents, and the risk of escalation. Competition over what are likely to be enormous oil and gas reserves is a major reason for this new dynamic, but there are other forces also contributing to brinkmanship in the region, including Turkey’s relations with the European Union, domestic political considerations in Ankara, and the deteriorating Turkey-Israel relationship.

In December 2010, Cyprus and Israel signed a maritime border agreement. Turkey opposed the agreement, pending a solution to the Cyprus conflict, and generally contests the application of the principles of the United Nations Convention on the Law of the Sea in delimiting maritime boundaries in the Mediterranean.

Ankara claims that the jurisdiction of the “Turkish Republic of Northern Cyprus” has been ignored and that energy resources in Cyprus’ exclusive economic zone should benefit all Cypriots, a point accepted in principle by the leaders of the two communities on the island. But on September 19, exploratory drilling for gas began in the Aphrodite gas field, off Cyprus’s southern coast. This field is adjacent to the larger Leviathan field, which the Texas company Noble Energy discovered last year off the coast of Israel. Overall, the U.S. Geological Survey estimates that the Levant Basin, adjoining Israel, Cyprus, Lebanon, Syria, and Gaza, contains 122 trillion cubic meters of recoverable natural gas, equivalent to 20 billion barrels of oil.

With the start of drilling, Turkish comments have become increasingly harsh. On September 21, Turkey’s Prime Minister Recep Tayyip Erdogan said in New York that “the Greek Cypriot administration and Israel are engaging in oil exploration madness in the Mediterranean,” and proceeded to sign a martime boundary agreement with Turkish Cypriot leader, Dervis Eroglu.

On September 23, Turkey was set to react to the start of drilling by sending a Turkish vessel, Piri Reis, accompanied by three frigates, to explore the continental shelf northwest of Cyprus, which includes areas claimed by both Greece and Cyprus. At the same time, the Turkish energy minister announced the blacklisting of companies involved in prospecting on behalf of the Greek Cypriots. The Greek embassy in Ankara has called on Turkey to respect Greece’s sovereign rights.

High stakes in terms of gas and oil reserves only partly explain recent tensions as other factors are also at work. Turkey sees Cyprus as an obstacle to its EU accession process. Cyprus has blocked six negotiating chapters — including the energy chapter, in spite of Turkey’s support for the Nabucco pipeline project — because of Turkey’s refusal to open its ports and airports to Cypriot flag carriers, in line with the protocol extending the EU-Turkey association agreement to new member states. The EU itself has blocked eight chapters for the same reason. “If the [Cyprus] peace negotiations are not conclusive and the EU gives its rotating presidency to southern Cyprus, the real crisis will be between Turkey and the EU,” Turkish Deputy Prime Minister Besir Atalay declared on September 19. “Our relations with the EU will come to a sudden halt.”

Turkey’s brinkmanship also reflects domestic political considerations. A tough line on Cyprus mobilizes support across the political spectrum, at a critical time when parliamentary votes are being assembled for a referendum on constitutional amendments establishing a presidential system of government in Turkey.

Against the background of the Arab Spring and the Palestinian bid for UN recognition, much attention has also focused on the relationship between Turkey and Israel. Since Ankara downgraded its relations with Israel, there have been significant rapprochements between Israel and both Cyprus and Greece. Threats by Turkey to mobilize its navy in support of energy exploration vessels resonate with similar suggestions, later denied, regarding another Gaza flotilla. While the two situations are distinct, they seem to be conflated in the current view from Ankara. Cooperation between Israel and Cyprus, which are both perceived in Ankara as antagonists, must have touched a raw nerve.

The United States, European Union, and United Nations have all expressed concern about risks to security in the eastern Mediterranean. Brinkmanship is ill-advised, particularly given that settlement talks are due in New York in late October. Friction over maritime resources adds to more acute regional tensions. Friends of Turkey and Cyprus need to engage with both parties in order to reduce tensions, focusing attention on progress towards a settlement and, if possible, keeping Turkey’s accession process to the European Union on track.

Michael Leigh is a Senior Adviser with the German Marshall Fund of the United States in Brussels.