“Turkey will get back its fair share in the Mediterranean, Aegean and the Black Sea,” Turkish President Recep Tayyip Erdogan declared in August. It was a bold statement in an increasingly heated dispute over maritime boundaries. What does Mr Erdogan see as fair? The answer lies in Turkey's latest foreign policy doctrine “Mavi Vatan”, or “Blue Homeland”, an irredentist vision that aims to resuscitate an almost-Ottoman level of maritime influence. In the mid-16th century, the Ottoman Empire held sway over the entire Mediterranean Sea, mainly thanks to a pair of bold seafaring brothers. Born on what is now the Greek island of Lesbos, Oruc and his younger brother Khizr emerged as internationally renowned corsairs for hire. The brothers gained the backing of one of the world’s most powerful leaders, Yavuz Sultan Selim, and built a capable Ottoman navy. The empire soon extended its reach to Algeria, and after Khizr, by then known as Barbarossa (“red beard”), defeated a Venetian-Spanish alliance off the Greek coast in 1538, the Ottomans controlled all the islands in the Aegean. Most historians view the brothers as pirates and slave traders, yet Turkish schoolchildren are taught the brave exploits of Oruc Reis (Turkish for “chief”) and Barbarossa Hayrettin (“best of the faith”). Now, Mr Erdogan uses seismic research vessels named after them to signal his country’s desire to defend its maritime rights and challenge regional powers. Devised by retired naval officer Cem Gürdeniz, it views the eastern Mediterranean, the Aegean and the Black Sea – to be Turkey’s Blue Homeland. It first made headlines a year ago when Mr Erdogan gave a speech in front of a map laying out Turkish control over more than 460,000 square kilometres in those three seas. Two weeks ago, the Turkish presidency marked the anniversary of that 1538 victory over Christian powers with a video re-enactment of Hayrettin battling Crusaders. “The blood of my ancestors flows through my veins,” the President’s communications head, Fahrettin Altun, said in a tweet releasing the video. “We die and take lives for the blue homeland.” The appearance of the Turkish survey vessel <em>Oruc Reis</em> and its accompanying warships in waters off the Greek island of Kastellorizo last month spurred Athens to place its armed forces on high alert, putting the fellow Nato members on the verge of war. Only when the <em>Oruc Reis</em> returned to port in Antalya a few weeks later were Turkey and Greece able to begin preliminary talks. The same day, however, another ship, the <em>Barbaros Hayrettin Pasha</em>, was sent to drill in waters claimed by Cyprus, where it is expected to remain until the second week of November. Over the past two years, Turkey has sent half a dozen research vessels accompanied by warships to drill in waters claimed by Cyprus. Last year, it signed a maritime borders deal with Libya’s Tripoli-based Government of National Accord that vastly expands its Mediterranean claims, enveloping all of the waters around the Greek island of Crete. Yet this maritime assertiveness is less about natural gas and potential energy revenues than it might appear. For one thing, most analysts are now convinced that any natural gas recovered from the eastern Mediterranean will be unlikely, by the time it reaches the market, to find buyers in either Europe or Asia. In line with Blue Homeland, Turkey has in recent years sharply increased its naval power. This includes domestically produced ships and submarines and a light aircraft carrier due next year. It has flexed this renewed maritime might repeatedly in drills at sea, with another planned for later this month. But the flexing is not only at sea. The naval build-up is part of a massive expansion of Turkey’s arms industry that has instilled greater military assertiveness. Turkey has a troop presence or is backing proxy forces in as many as seven Arab states – Qatar, Iraq, Syria, Libya, Sudan, Somalia and possibly Yemen – and has begun using foreigners to fight its wars. Thanks to Turkey’s sizable footprint in northern Syria, Mr Erdogan is able to dispatch thousands of Syrian rebels to fight in Libya and in the latest Armenia-Azerbaijan conflict for little pay. This avoids the potential political disaster of Turkish troops returning from some distant conflict in body bags, which would be a particularly bitter pill during an acute economic crisis. Such practices, however, draw regional ire. Last month, Egypt called on allies in the Arab League to join forces to counter Turkish aggressions in the region, particularly in Syria. Saudi Arabia has been boycotting Turkish goods for more than a year, and recent reports suggest that Oman, Bahrain and others might soon join that effort. What about foes further afield? A key element of Blue Homeland is a worldview that blames Turkey’s troubles on Western powers and positions the US and Europe as rivals, in spite of their formal military alliances with Ankara. But the US is neck-deep in a presidential election season while its leader struggles to beat covid-19 on multiple levels. And though Nato is hoping to broker Turkey-Greece talks, the EU has done little more than repeatedly denounce Turkish aggressions and warn of sanctions. At a summit early this month, EU leaders kicked the sanctions can down the road yet again, to a December meeting. The clock is ticking. On the sidelines of the latest session of the UN General Assembly in New York, the main actors in Libya inched toward a peace deal. As things stand now, any resolution to that conflict is likely to leave the GNA in control of Tripoli, which would encourage Turkey to fulfil the ambitions of its maritime borders deal and extend drilling further into the Mediterranean. The <em>Oruc Reis</em> left port and headed into open waters last week. Days later, Turkish news outlets reported that its next drilling destination would be Crete. <em>David Lepeska is a veteran journalist who has been covering Turkey for the past decade</em>