Saudi Arabia said Friday it shut down a major pipeline a day after it was attacked by drones, and Yemen’s Iranian-backed Houthi rebels captured a strategic island at the southern entrance to the Red Sea, two officials said, opening a new front in the Iran war.

The Houthis made their biggest territorial gains in years along the Bab el-Mandeb Strait, one of the world’s key shipping lanes. The advance could boost Iran’s strategy of driving up world oil and gas prices to pressure the United States.

Saudi Arabia said it had shut down the East-West pipeline after it was attacked the day before, with the energy ministry calling the move “a precautionary measure.”

The Saudi foreign ministry blamed the attack on several drones from Iraq that it said “caused human injuries and damage.” In a statement carried by the state-run Saudi Press Agency, the kingdom said it would not respond to give the Iraqi government “an opportunity to take the necessary measures.” But it also stressed that Saudi Arabia “reserves the right to take all necessary measures to protect its sovereignty, its security, its facilities,” and its inhabitants.

The Iraqi government condemned the assault, with the prime minister’s office announcing the dismissal of a military commander after investigations confirmed the attack originated from Iraq. Two Iraqi sources later told Reuters that Iraq ordered the closure of the Shalamcheh border crossing with Iran as a precautionary measure, adding that a wide-scale operation was underway to pursue the perpetrators of the attack.