Iraqi forces are facing their first real test since last month’s withdrawal of US troops, with a largescale security operation underway for a major religious pilgrimage.Some 6 million Shi’ite Muslims are expected to pay homage to the Iman Moussa al-Kadhim Shrine in northern Baghdad. In recent years, the event, which culminates later today, has seen some of the deadliest attacks on Iraqi civilians since the US-led invasion in 2003. Next January’s national elections loom large and Iraqi Prime Minister Nuri al-Maliki has staked his reputation on better security. Such religious gatherings are frequently targeted by Sunni extremists and the site has been surrounded by three rings of security personnel to search each pilgrim. Despite those efforts, some bombers have made it through. On Friday, a roadside blast in the south east of the Iraqi capital killed one pilgrim and wounded six others.