In mid-October, with unrest swirling in Baghdad, a familiar visitor slipped quietly into the Iraqi capital. The city had been under siege for weeks, as protesters marched in the streets, demanding an end to corruption and calling for the ouster of the prime minister, Adil Abdul Mahdi. In particular, they denounced the outsize influence of their neighbor Iran in Iraqi politics, burning Iranian flags and attacking an Iranian consulate. The visitor was there to restore order, but his presence highlighted the protesters’ biggest grievance: he was Maj. Gen. Qassim Suleimani , head of Iran’s powerful Quds Force, and he had come to persuade an ally in the Iraqi Parliament to help the prime minister hold onto his job. It was not the first time General Suleimani had been dispatched to Baghdad to do damage control. Tehran’s efforts to prop up Mr. Mahdi are part of its long campaign to […]