12 Nautical Miles: The Line That Could Start a War

Six nautical miles. A distance so short a speedboat covers it in a few minutes. And yet, if that number grows just a little larger — not through war, not through invasion, but through a signature under a piece of legislation — Turkey has officially declared that this would mean war. And that declaration remains active today. Two countries, both members of the very same military alliance, with a parliamentary decision hanging over a stretch of sea a few hundred kilometers wide, like a loaded gun.

The term is casus belli — Latin for "cause for war" — and it is not a figure of speech. On the eighth of June, nineteen ninety-five, the Turkish Grand National Assembly passed, unanimously, with every party in parliament in agreement, a resolution granting the Turkish government full and standing authorization to use military force if Greece ever extended its Aegean territorial waters beyond six nautical miles. This was not a politician's remark in an interview. It was the official position of an entire parliament, recorded in the minutes, and it technically remains in force today. One detail is worth pausing on: the party that governs Turkey today did not even exist in ninety-five — it was founded six years later. The resolution is not one government's policy. It is a position of the Turkish state itself, passed unchanged from one generation of leaders to the next.

To understand why two countries hang their fate on this one number, we have to go back to nineteen thirty-six. That year, Greece and Turkey each adopted, by their own separate laws, six nautical miles as the width of their territorial waters — a distance of roughly eleven kilometers, close to the three miles that was then the common international standard. For decades, this balance bothered no one. The Aegean stayed divided between Greek waters, Turkish waters, and a vast middle zone of open sea, free for everyone.

Those three miles it replaced were not an arbitrary number to begin with. They trace back to the seventeenth and eighteenth centuries, when Europe's naval powers decided that a nation's sovereignty over the sea reached exactly as far as a cannon fired from its coast could reach — the so-called "cannon-shot rule." That distance, roughly three nautical miles, slowly hardened into international custom. When Greece and Turkey chose six, in nineteen thirty-six, they were essentially doubling a rule that already outran the range of any real cannon — an early sign that, in this particular sea, numbers rarely stay where their original logic put them.

That balance began to crack in nineteen eighty-two, when the United Nations adopted a new convention on the law of the sea, known internationally as UNCLOS. It entered into force in nineteen ninety-four and established a global standard of twelve nautical miles for every coastal nation's territorial waters — a right, not an obligation, that any state can exercise whenever it chooses. This was no accident of timing. Dozens of newly independent states had emerged from postwar decolonization, and technology now allowed oil drilling far further from shore than ever before; everyone wanted greater control over the sea and the resources beneath it. Most of the world adopted the twelve-mile standard without a second thought — a routine matter, almost administrative. In the Aegean, though, that same right became the core of a crisis that continues to this day.

Greece ratified the convention that same year, nineteen ninety-five, through an act of its own parliament, explicitly stating that it reserves the right to extend its territorial waters to twelve miles whenever it sees fit, with no timeline attached. Turkey, by contrast, has never ratified that same convention — it is one of the very few countries in the world outside UNCLOS. And here lies the story's first contradiction: a country that refuses to be bound by a treaty simultaneously treats the exercise of a right that same treaty grants to every coastal state as an act of war.

Turkey's argument, though, is not only legal — it is geographic, and it deserves to be understood, not simply dismissed. The Aegean is not open ocean. It is a narrow, enclosed sea, scattered with hundreds of Greek islands that, in many places, sit just a few miles from the Turkish coast. In a geography like that, the number of miles is not a technicality. It is what decides how much of the sea belongs to whom.

Today, with both countries at six miles, Greece controls roughly forty-three point five percent of the Aegean's surface, Turkey barely seven point five percent, and the rest — nearly half — remains international, open water. If Greece exercised its right and extended to twelve miles, Greece's share would jump to seventy-one percent, Turkey's would stay almost unchanged, around nine percent, and international waters would shrink to a thin twenty percent. That number, not some abstract principle, is the real heart of Ankara's fear. And this is not just a matter of color on a map. Territorial waters decide who controls fishing rights, who has a say over undersea cables and pipelines, who can bar foreign warships from passing without notice, even how aircraft are allowed to fly overhead. A change in the miles is, in effect, a change in who decides almost everything above and below that water.

For Turkey, an Aegean that is almost entirely Greek is not just symbolic — it is a practical obstacle. Turkish ships, both commercial and military, would have to constantly cross Greek territorial waters just to reach the Mediterranean. Ankara calls this the "closing" of the sea, and invokes an article of that same UNCLOS convention — which it has never even signed — arguing that such an extension, in such an enclosed sea, would amount to an abuse of rights. The Greek side answers that no other coastal state in the world has ever accepted limiting its own sovereign right because it inconvenienced a neighbor, and points out that Turkey itself keeps twelve miles in the Black Sea — it is only in the Aegean that it insists on six.

Greece, for its part, has not left that right sitting only on paper. In two thousand twenty-one, the Greek parliament passed a law extending its territorial waters in the Ionian Sea from six to twelve nautical miles. No crisis followed, because there is no Turkish coast on the other side there. That very same right, exercised in the Aegean, would trigger — at least on paper — a declaration of war. The law is identical. It is the map that changes everything.

This is not a theoretical matter for lawyers. The Aegean has already come within a breath of armed conflict over something far smaller than territorial waters — two uninhabited rocky islets, so small they barely fit on an ordinary map, known in Greece as Imia and in Turkey as Kardak. In January nineteen ninety-six, a shipwreck, a disputed flag, and a helicopter that never came back brought the two countries so close to war that only a late-night phone call from Washington prevented the worst. Three Greek officers never returned from that night. Ankara named Imia, and dozens of other islets across the eastern Aegean, "grey zones" — areas where it considers sovereignty unresolved, while Athens regards them as unquestionably Greek. That is a story that deserves its own chapter, and you will hear it in the next book of this series. For now, hold on to this: ambiguity over a few square meters of rock managed to do what, in theory, a line of twelve miles could also do.

And this is not something that stayed frozen in nineteen ninety-six. Greece's General Staff of National Defence records, year after year, thousands of territorial-water violations by Turkish warships, coast guard vessels, and fishing boats — more than one thousand five hundred in two thousand twenty-two alone, and again in two thousand twenty-three, according to its own official figures. Ankara, for its part, reports thousands of its own alleged "violations" by Greek ships and aircraft. Each side keeps its own ledger, measuring the same stretch of sea with a different ruler. The result is not war — it is a quiet, unrelenting friction, playing out day after day on exactly the issue the nineteen ninety-five resolution tried to freeze once and for all.

The strangest thing about this entire story is exactly where it happens: between two countries that are, on paper, allies. Greece and Turkey have both been members of NATO since nineteen fifty-two, an alliance built explicitly so its members would defend one another against outside threats. And yet, for more than three decades, one member has held an official declaration of war against the other. Greece tried to use that very paradox as leverage: at the European Union's Helsinki summit, in December nineteen ninety-nine, Athens lifted its veto and agreed to let Turkey become a candidate for EU membership — but on one condition: Turkey was called on to accept the jurisdiction of the International Court of Justice in The Hague over the Aegean disputes, by two thousand four at the latest. That deadline passed unmet, the casus belli issue remained untouched, and its repeal remains, to this day, a stated Greek precondition for any meaningful progress in Turkey's path toward the European Union.

The issue did not stay frozen in the nineteen-nineties. In January of two thousand twenty-six, Greece's foreign minister reaffirmed in parliament Greece's intention to eventually extend its territorial waters in the Aegean, citing precedent from its maritime boundary agreements with Egypt and Italy. A few months later, Turkey advanced its own draft maritime law, part of the doctrine it calls "Blue Homeland" — an idea that is not new. It was coined, in two thousand six, by a Turkish naval officer at the time, Cem Gürdeniz, who wanted to give a name and a plan to Turkey's maritime jurisdiction claims. For years it remained a fairly marginal idea. After the failed coup attempt of two thousand sixteen, though, it was fully adopted as official Turkish policy, and this year's draft law explicitly locks in the six-mile limit in the Aegean as non-negotiable. To this day, neither side has taken the step that would actually redraw the map.

And this, perhaps, is the most interesting part of the whole story: more than three decades after the nineteen ninety-five resolution, neither side has pulled the trigger. Greece has not extended its territorial waters in the Aegean, even though it considers this an inalienable right. Turkey has not declared war, even though it has held the official authorization to do so for decades. The casus belli functions like a loaded gun sitting on a negotiating table: no one fires it, but no one dares touch it either.

International law, in the end, is not what will resolve this story on its own. It states clearly what Greece's right is. It says nothing about what Turkey would actually do if that right were exercised, nor can it force a country to withdraw a declaration of war it voted for itself. Between what a law permits and what an armed neighbor will actually tolerate in practice, there opens a gap that no convention has yet managed to close — and inside that gap, for more than three decades, the entire Aegean has lived.

A nautical mile is just one point eight kilometers — a distance you could cover on foot in twenty minutes. Six such miles today separate peace from an official declaration of war between two NATO allies. It is a reminder that the world's most dangerous borders are not always drawn on land, with walls and barbed wire. Sometimes they are invisible, written across water, measured in miles that neither side has yet dared to cross.