When a Saudi state executioner beheaded the prominent Shiite dissident Sheikh Nimr al-Nimr on Saturday, the Shiite theocracy in Iran took it as a deliberate provocation by its regional rival and dusted off its favored playbook, unleashing hard-liner anger on the streets. Within hours of the execution, nationalist Iranian websites were calling for demonstrations in front of the Saudi Embassy in Tehran and its consulate in the eastern Iranian city of Mashhad. The police, outnumbered, looked the other way as angry protesters set the embassy ablaze with firebombs, climbed the fences and vandalized parts of the building. Now, Iranian leaders are suddenly forced to reckon with whether they played into the Saudis’ hands, finding themselves mired in a new crisis at a time they had been hoping to emerge from international sanctions as an accepted global player. Iran might have capitalized on global outrage at the executions […]