Tensions between Iran and Saudi Arabia, Islamic rivals of the Middle East, appeared to escalate on Wednesday over the Sunni extremist insurgency convulsing Iraq, as President Hassan Rouhani of Iran declared readiness to defend Iraq’s Shiite holy sites with force and Saudi leaders issued a barely veiled admonishment not to intervene. The sharpened tone coming from both countries, which have long regarded each other with suspicion — Iran is overwhelmingly Shiite and Saudi Arabia Sunni — suggested that their recent tentative efforts to improve relations might be faltering over the Iraq crisis. Both countries have long vied for influence in the region and support opposing sides in Syria’s civil war. The Saudis are also increasingly concerned about Iran’s efforts to ease its longstanding estrangement with the United States, a close strategic and economic partner of Saudi Arabia. While the United States and Iran differ on many issues, most notably […]