Nouri al-Maliki took a huge gamble this week when he ordered the Iraqi army into battle against Shia militias in the southern port city of Basra.

If the prime minister succeeds, the pay-off would deliver a big boost to the credibility of a shaky government, proving that the growing national army is capable of taking on powerful militia and addressing fears that a withdrawal of US troops would leave Iraq’s fragile state at the mercy of armed factions.