The final push will be led by Iraqi’s U.S.-trained Counter Terrorism Service units, the same forces that first entered the eastern reaches of the city in October when the battle to retake the city began, officers said. The plan involves clearing the final few neighborhoods north of the Old City and surrounding the square-mile-wide neighborhood.

With tens of thousands of civilians packed into an area defended by Islamic State fighters, snipers and car-bombers, the battle could quickly turn into a humanitarian crisis.

Some Iraqi military commanders say they are trying to finish the battle in the next two weeks, before the holy month of Ramadan begins and many soldiers will begin fasting during the day. Yet with the Islamic State still doggedly fighting for each block, it is unclear whether the campaign will end any time soon.

Lt. Gen. Sami al-Aridhi, the commander of two counterterrorism task forces, estimates that there are between 250 to 350 Islamic State fighters, many of them French and Russian, in the Old City, along with more than 200,000 civilians.