ISIS obviously doesn’t have the manpower to control all of Baghdad so they will reportedly attempt to control swaths of territory in the western part of the city.

(Reuters) – Iraqi insurgents are preparing for an assault on Baghdad, with sleeper cells planted inside the capital to rise up at “Zero Hour” and aid fighters pushing in from the outskirts, according to senior Iraqi and U.S. security officials.

Sunni fighters have seized wide swathes of the north and west of the country in a three week lightning advance and say they are bearing down on the capital, a city of 7 million people still scarred by the intense street fighting between its Sunni and Shi’ite neighborhoods during U.S. occupation.

The government says it is rounding up members of sleeper cells to help safeguard the capital, and Shi’ite paramilitary groups say they are helping the authorities. Some Sunni residents say the crackdown is being used to intimidate them.

Iraqis speak of a “Zero Hour” as the moment a previously-prepared attack plan would start to unfold.

A high-level Iraqi security official estimated there were 1,500 sleeper cell members hibernating in western Baghdad and a further 1,000 in areas on the outskirts of the capital.

He said their goal was to penetrate the U.S.-made “Green Zone” – a fortified enclave of government buildings on the west bank of the Tigris – as a propaganda victory and then carve out enclaves in west Baghdad and in outlying areas.