Competition over gas discoveries in the eastern Mediterranean has combined with bitter regional rivalries to fuel dangerous tensions between Turkey and its neighbours in recent months.
Many fear this could lead to direct military confrontation between Turkey and Greece, as the two Nato members and their allies square up over control of the seas.
Germany warned last month that Greece and Turkey were “playing with fire” and that “the smallest spark could cause disaster”.
Here’s what you need to know to understand the stand-off on the EU’s doorstep:
What are the competing claims?
Turkey and Greece have a decades-long dispute over their maritime boundaries that has never been resolved. The Turkish coastline is dotted with Greek islands that Athens believes bestow Greece with territorial rights. Ankara argues they violate its own maritime claims.
Ankara claims that islands should only have limited exclusive economic zones (EEZs). It points to previous international rulings that limited the influence of islands in determining maritime boundaries, such as in a 1982 dispute between Libya and Tunisia.
Ankara’s position is complicated by its refusal to sign the UN Convention on the Law of the Sea, which is normally called on to resolve such disagreements.
A related quarrel centres on the divided island of Cyprus. Ankara sees itself as a protector of the Turkish-speaking northern part of the island, which it invaded in 1974 after a Greek-backed coup.
But the Turkish Cypriot self-declared state is not recognised by the international community, which views the government on the Greek Cypriot side as the legitimate authority for the whole island. Cyprus was contentiously admitted to the EU in 2004.
Turkey believes that the government that sits in southern Cyprus should not have the right to auction blocks of its surrounding seabed to international energy companies until Turkish Cypriots can share the benefits. But peace talks have failed multiple times in the past 45 years.
Turkey also believes its own southern coastline gives it economic rights in waters off Cyprus that Nicosia sees as part of its territory.
Where has gas been discovered?
The discovery of the supergiant Zohr gasfield off Egypt in 2015 kickstarted interest in the region from some of the world’s largest energy companies. Italy’s Eni, which discovered the Zohr field, started production in 2017, generating billions of dollars in revenues annually.
But it was not the first significant find. Israel struck reserves in 2009, followed by the larger Leviathan field in 2010. With little existing infrastructure, these took time to develop but have since slashed Israel’s reliance on highly polluting coal for electricity.
Cyprus first discovered gas in 2011. Two other significant finds by energy majors including Eni, Total and ExxonMobil followed in 2018 and 2019.
Most of the discoveries so far have been in the south-eastern portion of the region, close to Egypt, Israel and Cyprus’s southern coast. The areas where Turkey is drilling for gas do not yet have proven reserves.
But work to assess and develop these prospects has largely been delayed this year because of the slump in energy prices during the coronavirus pandemic.
Why does Turkey feel isolated?
The development of gas resources in the eastern Mediterranean has forged some unlikely alliances. The EastMed Gas Forum, nicknamed “the Opec of Mediterranean gas” was formally established in Cairo this year.
It brings together Egypt, Israel, the Palestinian Authority, Jordan, Greece, Cyprus and Italy, with the aim of establishing the region as a major energy hub. France has asked to join, while the US has requested to become a permanent observer.
That has left Turkey isolated because of its tensions with many members, including Greece and Egypt, even as the forum has helped to forge common ground between Israel and a number of its neighbours.
Turkey’s foreign ministry in January decried the forum as an “unrealistic formation” and accused it of seeking to exclude Ankara.
What does this have to do with the war in Libya?
Tensions in the eastern Mediterranean are increasingly tangled up with the conflict in Libya, where a civil war has morphed into a proxy struggle between rival international powers.
Turkey backs the UN-endorsed Libyan government in Tripoli that has been fighting renegade general Khalifa Haftar, who has received support from nations including Russia, Egypt, the United Arab Emirates and France.
In November, Turkey and Tripoli signed a pair of landmark deals. One laid the groundwork for Ankara to provide the beleaguered government with game-changing security and military support. Over the months that followed, it shifted the balance of the war in the Tripoli-based government’s favour.
The second agreement demarcated a new sea boundary between Turkey and Libya, angering Greece and complicating plans for a future pipeline from Cyprus to Greece, via Crete, that could pipe gas to mainland Europe.
As Turkey’s influence in Libya increased, countries such as the UAE and France have become increasingly vocal about the dispute in the east Mediterranean. Both nations dispatched forces to join recent military exercises held by Greece and Cyprus in a show of strength against Turkey.
What does the international community think?
Nato talks aimed at reducing the risk of a military clash between the two alliance members got off to a difficult start last week, as Athens refused to participate while Turkey still had naval ships in contested waters.
While the US has called for a diplomatic solution to the crisis, it has been largely absent from efforts to prevent military confrontation between Greece and Turkey.
That job has fallen to the EU.
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The majority of member states favour dialogue and de-escalation with Turkey, which is an important partner economically, on migration and on Middle East regional security.
In July and August, Germany launched a mediation attempt between Athens and Ankara that stalled when Greece signed a new maritime deal with Egypt, angering Turkey.
But Greece and Cyprus have been pushing hard for the EU to take a tougher stance towards Turkey, including further sanctions. France is increasingly swinging towards the Greece-Cyprus position because of its own disputes with Turkey, particularly over Libya.
Other member states may also feel obliged to take a harder line if Turkey continues to press ahead with drilling — though there is little evidence so far of widespread support for sweeping economic sanctions.
This is all due to be discussed by EU foreign ministers and leaders later this month. Josep Borrell, EU foreign policy chief, has said that further countermeasures could include blocking Turkish companies involved in the energy controversy from using European ports, products and finance.
Video production by Tom Hannen
Graphics and cartography by Steven Bernard
Design by Kevin Wilson and Adam James
Produced by Adrienne Klasa