New Delhi, April 10 -- 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 ...