Oil has jumped to $100 a barrel as the Iran conflict flares back up — bad news for drivers, businesses, and anyone hoping the war was winding down.

• The U.S. blew up five Iranian oil tankers after Iran fired at Navy ships, and Iran hit back with its largest missile barrage of the war.
• Iran used cluster warheads for the first time, forcing air defenses to burn through huge numbers of Patriot missiles, some of which still failed to stop the attack.
• Patriot stockpiles are now running low, and replacements take about a year to build — a shortage that also delays weapons promised to allies.
• Claims that Iran's military was destroyed look wrong: it fired coordinated waves from across the country within hours of the tanker strikes.
• Washington added sanctions on more than two dozen Iranian airlines, squeezing Iran's economy but doing little to change the fighting.

Outlook: Iran has threatened tankers linked to Kuwait and Bahrain next, so oil could climb further and U.S. casualties may still be reported.