Anybody who’s old enough, or reads a little history, knows that the Arab oil shocks of the 1970s caused a lot of trouble. Gasoline and energy prices soared, shortages forced rationing, and America suddenly seemed vulnerable to the whims of oil sheikhs half a world away.

That sense of vulnerability persists. But maybe it shouldn’t. Oil shortages can still cause painful price spikes and other problems. But the US economy is now more durable, with much better defenses against the use of oil as an economic and political weapon.

Markets are grappling now with the right way to price the risk of a fresh oil shock to the US economy as Iran retaliates against joint US-Israeli attacks on its nuclear weapons program and a new Middle East war escalates. The shooting started with a June 13 Israeli blitz on Iranian nuclear facilities and other targets. On June 21, President Trump ordered US strikes with giant “bunker buster” bombs to destroy deeply buried nuclear sites that Israel lacks the firepower to reach.

Iran has been lobbing missiles at Israel since June 13, and on June 23, it fired missiles at US bases in Qatar and Iraq. The damage from those attacks appears to be limited. But Trump may feel obligated to fire back, and a widening war raises the stakes of economic blowback.

The biggest risk for markets is a disruption of Persian Gulf oil supplies, which could happen if Iran tries to block the Strait of Hormuz or destroy oil infrastructure in neighboring countries. Israel or the United States could also attack Iranian oil facilities, which would probably lead Iran to respond in kind. Or vice versa.

About 20% of the world’s oil leaves the Persian Gulf by ship, so any disruption would have an immediate effect on global supplies. The risk of a disruption pushed oil prices up modestly after the June 13 Israeli attack. Yet prices fell after the US upped the ante with the June 21 attack, and even as Iran retaliated against US bases on June 23.