Mosul - Counterattacks by ISIS (Daesh) militants on the western edge of Mosul have stalled Iraqi forces' push in the Old City, the last ISIS stronghold in the battle, an Iraqi officer said Tuesday. The attacks forced Iraqi forces and the U.S.-led coalition to pull some assets away from the Old City to again clear the Yarmouk and Tanak neighborhoods, which were declared liberated of ISIS in May. The assaults underscore the Sunni extremist group's resilience in the city, Iraq's third-largest, despite months of heavy fighting with Iraqi forces backed by U.S. air power. According to the Iraqi officer, who spoke on condition of anonymity in line with regulations, the latest counter-attacks began on Sunday by scores of ISIS fighters dressed as Iraqi Shiite paramilitaries. The following day, he said, a dozen coalition airstrikes on Mosul's western-most edge killed about 40 militants. The territory that ISIS group still holds in Mosul has been reduced to an area that now amounts to about 2 square kilometers (0.8 square miles) in the ancient Old City district.