According to a classified briefing to Congress, fully clearing Iranian mines from the Strait of Hormuz could take half a year — and the operation probably can’t even begin until the shooting stops. Here’s what that means for oil, the global economy, and anyone who pays a gas bill.

The Strait of Hormuz is 21 miles wide at its narrowest point. Through that 21-mile gap flows roughly one-fifth of the world’s seaborne oil supply — every single day, in peacetime. Right now it is not peacetime, and the Pentagon has quietly told Congress something that should probably be front-page news everywhere: even after a ceasefire, it could take up to six months to make that passage safe again.

The Washington Post first reported the assessment, citing officials familiar with a classified briefing given to House Armed Services Committee members. Pentagon spokesman Sean Parnell pushed back hard, calling the report based on “cherry-picked” information from a closed session and insisting the characterization was “false.” But he didn’t say six months was wrong. He said the framing was unfair. That’s a meaningful distinction — and a careful one.

“Asix-month closure of the Strait of Hormuz is an impossibility and completely unacceptable to the Secretary.”— PENTAGON SPOKESMAN SEAN PARNELL

The core problem is physical, not diplomatic. Iran’s Revolutionary Guards have warned shipping of a “danger zone” stretching across roughly 1,400 square kilometers — an area fourteen times the size of Paris — where mines may be present. And here’s the part that makes military planners lose sleep: according to one report, Iran itself has lost track of some of the mines it planted. That’s not spin. That’s a Navy nightmare. You can negotiate a ceasefire. You cannot negotiate with an untracked sea mine sitting 40 feet below the surface of a major shipping lane.

Mine clearance is slow, painstaking, dangerous work. It involves specialized vessels, underwater drones, sonar sweeps, and — when all else fails — controlled detonations. The US Navy began mine clearance operations in the strait in early April, but that effort was immediately disputed by Iran’s Revolutionary Guard, which threatened any military vessels attempting to enter. The operation has been contested from the start, and the Pentagon’s assessment apparently reflects what a realistic, uncontested clearance would actually require — not an optimistic scenario, but an honest one.

HOW WE GOT HERE — KEY TIMELINE

Mar 10US intelligence confirms Iran begins planting naval mines in the strait. First ship attacks reported.