54,000: Iraqi security forces
40,000: Peshmerga forces
14,000: Paramilitary units*
500: US forces, mostly for logistical efforts
*The paramilitary units include Shiites, Sunnis, Christians, Turkmen and Yazidis. Shiite members are assisting with, but not participating in, the Mosul offensive.
Source Article from http://www.cnn.com/2016/10/17/middleeast/mosul-isis-operation-begins-iraq/