Iran Strikes: What’s at Stake for Oil Markets as War Spreads

President Donald Trump’s decision to strike Iran creates new risks for a significant chunk of the world’s oil supply.

The Islamic Republic itself pumps more than 3 million barrels a day, or 3% of global output, making it the fourth-largest producer in OPEC. But the nation wields far greater influence over the world’s energy supplies because of its strategic location.

Iran sits on one side of the Strait of Hormuz, the shipping lane for about a fifth of the world’s crude from key suppliers including Saudi Arabia and Iraq. Traffic transiting the waterway dropped off sharply following the regional ...