Shiite rebels and allied troops overran the capital of an oil-rich Yemeni province in a heavily Sunni area on Thursday, making significant territorial gains despite Saudi-led airstrikes, now entering their third week.

Iran, which is trying to garner international support to stop the bombing, stepped up its condemnation, with the supreme leader calling the air campaign “genocide.”

The rebel fighters, known as Houthis, along with military units loyal to former autocrat Ali Abdullah Saleh, overran Ataq, the capital of oil-rich Shabwa province, after days of airstrikes and clashes with local Sunni tribes. […]