Saudi Arabia, Pakistan and Turkey have signed a joint defence agreement in Mecca, wedding Sunni Muslim US allies alarmed at a regional conflagration that has rained missile fire onto Gulf oil exporters. Iran and its allies have been firing on Saudi Arabia and other Gulf states, and blockading their energy shipments, since the US and Israel attacked it on February 28 in a major escalation of years of regional tumult. Saudi Arabia, the strongest Gulf state, is home to Islam’s holiest sites and one of the world’s top oil exporters, while Pakistan is the only nuclear-armed Muslim country. Tehran has attacked US bases and civilian infrastructure in Saudi Arabia, Kuwait, Bahrain, Qatar, the United Arab Emirates, Oman, Jordan and Israel. While Turkey and Pakistan, on the borders of the Middle East, have avoided significant direct attacks, both are anxious to calm conflicts that threaten their own security and economic health.