The East-West pipeline is about 1,200 kilometres long and carries Saudi crude oil across the country. On Monday the Houthis, an armed group in Yemen, said they had attacked its pumping stations and the airport in Riyadh, the capital. Saudi Arabia did not confirm the attacks.
The pipeline matters because the Strait of Hormuz, a narrow sea lane that ships normally use to leave the Gulf, has been largely shut by the war. That makes the pipeline an important way for oil to leave.
What does this mean at home? In the United States, the average price of a gallon of petrol was $4.28 on Sunday, according to the motoring group AAA. Oil prices eased on Monday after rising close to a six-month high last week.