Story highlights U.S. military official says there is a plan to retake Mosul from ISIS

Mosul would be attacked by Iraqi and Pershmerga forces, officials said

U.S. would only provide air support, no ground troops are planned, official said

ISIS issues new propaganda video showing peaceful scenes in Mosul

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.

The idea is for groups to enter Mosul and attempt to establish initial footholds. They would then seek to expand their areas of military control, pushing out the militant terror group that also refers to itself as Islamic State, according to the official.

U.S. and coalition aircraft would provide support from the air.

It is not expected that any U.S. troops would be on the ground to locate targets for aircraft to strike, but Iraqi and Peshmerga commanders could communicate targets to the coalition, the officials said.

The U.S. military is planning to train 12 Iraqi and Peshmerga brigades and plans to start arming members of the Sunni Anbari tribe, according to a military officials.

All of this will be a series of judgment calls and agreements with Iraqis as to how many troops are involved and when they're ready to go, the U. S. official said, and should not be thought of as set in stone.

ISIS released a new video Friday titled "A visit to Mosul", which shows peaceful scenes in the city and claims that Christians and Yazidis there have now "entered Islam." The video is in stark contrast to the violence usually shown in ISIS propaganda.