Iraq’s Shiite leaders called on their followers Friday to pick up weapons and join the government’s fight against Sunni militants who have closed in on the capital Baghdad, as the fears of the country’s Shiite majority mounted.

The call to arms issued during Friday prayers was another indication that the government of Prime Minister Nouri al-Maliki was incapable of mustering enough official forces for its defense.

Iran has already come to the aid of Iraq’s Shiite-dominated government, deploying Revolutionary Guard units to fight Sunni Islamist fighters and to guard the capital, as well as the Shiite holy cities of Karbala and Najaf. […]