The European Union's relationship with Turkey will be one of the main focuses of Germany's 6-month presidency of the Council of the European Union. "We need a coherent Turkey strategy," Chancellor Angela Merkel told the German Parliament on July 1. The EU's policy on Turkey would have to cover all that is relevant to its dealings with the country, she said, from issues regarding the conflicts in Syria and Libya and the question of refugee policy to human rights.

But Merkel named one issue a particular obstacle to good long-term relations between the EU and Turkey: Turkey's drilling, or plans to drill, for oil and gas off Cyprus and the Greek island of Crete. Drilling off Cyprus has been ongoing since 2019, while operations near Crete have been announced for fall of this year.

The quarrel has to do with Turkish claims to maritime territories in the eastern Mediterranean Sea. For decades, Ankara has been of the opinion that the many Greek islands off Turkey's Aegean coast should be entitled only to a much reduced Exclusive Economic Zone (EEZ), if any. An EEZ is a sea zone in which a sovereign state has special rights regarding the exploration and use of marine resources. EEZs are prescribed according to the United Nations' Convention on the Law of the Sea (UNCLOS) of 1982.

For instance, in an interview with the German daily Süddeutsche Zeitung in late June, Foreign Minister Mevlut Cavusoglu said it was unacceptable that the small island of Kastellorizo, which lies just off the Turkish mainland and is more than 500 kilometers (311 miles) from Athens, has a maritime jurisdiction area extending 200 nautical miles (230 miles, 370 kilometers) in every direction. "What country would accept such a situation?" he asked. 

The principle of fairness

However, despite Turkey's objections, Kastellorizo's claim to such an EEZ is fundamentally legitimate, according to Nele Matz-Lück, the co-director of the Walther Schücking Institute for International Law at Kiel University, in northern Germany. She cites the example of France, which claims several small islands in the South Pacific and Antarctic Ocean for itself along with the corresponding huge maritime territories.

Only islands that are inhabitable or can support independent economic activity can claim an EEZ of 200 nautical miles. However, if this zone overlaps with that of another state, both states have to come to an agreement on where the border lies within the framework of UNCLOS.

Matz-Lück says there less is regulation around what such an agreement should look like. "When states make a treaty, they are very free with regard to the method they use and what result they achieve. If such a case is brought before an international court or an international arbitrator, these are meant to make a decision according to principles of fairness and equity."

Such principles would also apply in the case of small Greek islands off the Turkish coast, Matz Lück says. "For reasons of fairness, in certain cases small islands may not be taken into account by courts of arbitration and international courts when drawing up borders, if they would lead to a distortion of the situation."

When is an agreement legally effective?

The Turkish government has announced it will start drilling for oil and gas near Crete in September. It cited the memorandum of understanding it signed with the UN-recognized Libyan government in November 2019 regarding the demarcation of maritime territories in the eastern Mediterranean. However, Greece and other Mediterranean countries have rejected this agreement, arguing the deal ignores the presence of Crete between the coasts of Turkey and Libya.

Matz-Lück has concluded that "even if [the treaty] was effectively concluded and has come into force, [it] cannot have effects to the detriment of a third state." She says a treaty between Turkey and Libya that completely ignores Greece's claims to sea zones can have no legal force at least with regard to Greece.

In contrast, she says the agreement reached by Italy and Greece in June, demarcating the EEZ of each state in the Ionian Sea, is effective in law. "The question of whether neighboring states have to be asked is decided according to whether there are overlapping borders. As a general rule, as long as a territory that is claimed by only two states is being demarcated, other states do not need to be included," Matz-Lück says.

She is equally clear on the question of Turkey drilling for oil and gas off the coast of Cyprus: "Even if the status of Northern Cyprus is highly controversial, Turkish oil and gas drilling on the Cypriot continental shelf is legally doubtful," she says, referring to the breakaway northern portion of the island that only Turkey recognizes and uses to back up its claims to drilling rights.

Matz-Lück also rejects Turkey's objection that it is not a signatory to UNCLOS and is therefore under no obligation to abide by it. She says many of the convention's regulations are now established in customary law, and even Turkey itself invokes them.

A possible solution for Greece, Cyprus and Turkey

Up to now, Greece and Cyprus have refused to negotiate with Turkey on the maritime border issue. They take the position that it has already been settled by international treaties. But it is questionable whether this position remains tenable. If Ankara, Athens and Nicosia were to decide to present the matter to an independent institution, the International Court of Justice in The Hague or an international arbitration tribunal would be possible options.

Until a ruling were to be handed down, the countries could agree on a temporary solution that provides for joint economic development of the disputed maritime territories, with no claims being made and no anticipation of the shape of a later agreement, Matz-Lück says. "Profits are shared until a border can, perhaps, be agreed upon one day," she says, adding that such  joint usage can ultimately become a permanent solution.