Weapon of mass disruption: Will the US and Iran strike a win-win deal on the Strait of Hormuz?

For centuries the so-called cannon shot rule determined who controlled the seas. The legal concept, codified by Dutch jurist Cornelius van Bynkershoek in 1702, was simple: The distance a cannonball reached from shore set the maritime boundary of a coastal state.

Fast forward 300-plus years and little seems to have changed, only the weapons. Today, missiles and drones draw the limits.On Tuesday night, the US and Iran agreed to a tentative two-week ceasefire that pauses a six-week conflict that many have already—and rightly—called the War of Hormuz because of the central importance of the stretch of water that goes by that name.

What follows will demand the ultimate feat of linguistic gymnastics from diplomats and negotiators working on a lasting peace: they’ll need to square a circle over how the strait is governed, letting both Washington and Tehran claim they got what they wanted.One thing is clear: No matter how one dissects the American and Iranian statements about the ceasefire, the strait’s status has changed. What was a free waterway before the hostilities began is today—at the very least—a controlled one.

Its future is up in the air, and with it the seaborne passage of a fifth of the world’s oil and liquefied natural gas supplies.Can the strait return to its prewar status, effectively subject to the United Nations Convention on the Law of the Sea, allowing free passage, unimpeded by tolls and fees? Maybe, but I doubt it. Neither Iran nor the US has ratified that UN treaty, even if both effectively followed some of its provisions.