Four aerial images released by Stratfor security analysis company show barricades and berms erected by the militants in the streets of Mosul.

Buildings have been razed to clear the view, according to Startfor.

Iraqi regular troops and special forces, Shi'ite militias, Kurdish peshmerga fighters and other groups backed by US-led air strikes launched their campaign to retake Mosul nearly three weeks ago.

Iraqi special forces said they recaptured six districts of eastern Mosul on Friday (November 4).

So far Iraqi troops have gone one mile (1 1/2 km) inside the city, after recapturing villages on the outskirts of Mosul.

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