A military plan to retake the northern Iraqi city of Mosul from ISIS could begin as soon as January using Iraqi and Kurdish Peshmerga forces, a U.S. official confirmed to CNN.

The current plan is to assemble about 1,000 troops, with Iraqi forces approaching Mosul from the south and Peshmerga forces from the west, said the official, who spoke on the condition of anonymity. But everything in the plan is “conditions based,” and the exact timing and size of the force to be used remains to be determined, the official said.

It’s unclear how long such an operation would take to be successful. […]