Iran Deploys Quds Force To Save Iraq's Shia-Led Regime

This video shows a Sunni tribal fighter explaining how the capture of 2 Iranians attempting to infiltrate into Fallujah.

The threat of Sunnis eclipsing the power of its Shiite-dominated Arab ally presents Iran with the biggest security and strategic challenge it has faced since the U.S.-led invasion of Iraq in 2003.

Iran deployed Revolutionary Guards units to Iraq, according to Iranian security officials.

Iran has invested considerable financial, political and military resources over the past decade to ensure Iraq emerged from U.S. war as a strong Shiite-led state. The so-called Shiite crescent—stretching from Iran to Iraq, Lebanon and Syria—was forged largely as a result of this effort.

Two Guards' units, dispatched from Iran's western border provinces on Wednesday, were tasked with protecting Baghdad and the holy Shiite cities of Karbala and Najaf, these security sources said.

Syria's conflict has turned Iraq into an important operational base for Iran to aid another ally, the Assad regime, which is dominated by an offshoot of Shiite Islam. Shiite militia trained by Iran, weapons and cash have flowed from Iran to Syria via Iraq.

"Iraq is viewed as a vital priority in Iran's foreign policy in the region and they go to any length to protect this interest," said Roozbeh Miribrahimi, an independent Iran expert based in New York.

Iran has also positioned troops on full alert along its border with Iraq and has given clearance to its air force to bomb rebel forces, according to an Iranian army general.

The two IRGC battalions that moved to Iraq on Wednesday were shifted from the Iranian border provinces of Urumieh and Lorestan, the Iranian security officials said.

Revolutionary Guards units that serve in Iran's border provinces are the most experienced fighters in guerrilla warfare because of separatist ethnic uprisings in those regions. IRGC commanders dispatched to Syria also often come from those provinces as well.

Iran was also considering the transfer to Iraq of Shiite volunteer troops in Syria, if the initial deployments fail to turn the tide of battle in favor of Mr. Maliki's government, the Iranian security officials said.