Iraqi government forces, backed by Shia Muslim and Kurdish militias, are reportedly holding back an advance by Sunni militants north of Baghdad. A number of towns have been retaken from the rebels, but they still control the key cities of Tikrit and Mosul.

Iraq’s most senior Shia cleric, Grand Ayatollah Ali al-Sistani, has issued a call to arms to fellow Shia, and there are reports that thousands have already joined militias.A US aircraft carrier has been deployed to the Gulf in response to the escalating violence and there are reports that government forces are building up in the city of Samarra, apparently preparing for a counter-offensive designed to drive rebels out of Saddam Hussein’s hometown, Tikrit, to the north.

The BBC’s experienced correspondent John Simpson says:

Since Thursday, the idea that Shia fighters, Shia volunteers should come forward and back the army up has restored a certain amount of balance here.

Of course you could say that’s a problem for the future of this country, if one religious group is setting out to fight another one – and that blatantly. But that is something else, something for the future. For the moment it seems that there is a bit of a sense that things are settling down.

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