Yemen’s Iran-backed Houthis attacked a Saudi Aramco refinery on Sunday, two days after Saudi Arabia forged a defense pact with Turkey and Pakistan. The alliance pledges mutual defense, which means an armed attack on any one member counts as an attack on all. But after Sunday’s attack, it was not immediately clear whether Turkey or Pakistan would respond. The Houthis also attacked the Yemeni Red Sea port city ​of Mokha, close to the strategic Bab el-Mandeb Strait, killing at least seven people. Last month, Houthi leaders declared a naval blockade against Saudi Arabia, claiming a Saudi siege on the militia group.