As of Monday, the United States announced it would begin guiding ships through the Strait of Hormuz with the support of guided-missile destroyers, more than 100 aircraft, and 15,000 service members. A tanker was struck by unknown projectiles in the strait within hours of the announcement. The dual blockade — the U.S. Navy preventing access to Iranian ports while Iran restricts commercial shipping through the strait — has now entered a phase where each side is testing the other’s escalation threshold in a waterway that carries roughly one-fifth of daily global oil production.