In the first phase of a long-planned military operation to liberate Mosul from the Islamic State, Iraqi forces, supported by US-led airstrikes and special forces along with Peshmerga, the Kurdish forces, advanced on Mosul from the east and the south on 17 October.
The second largest city of Iraq, Mosul, has been under ISIS' control where the terrorist organisation's leader Abu Bakr al-Baghdadi declared the establishment of a caliphate two years ago.
According to The Guardian, Kurdish leaders claim their forces had captured 200 sq km (77 sq miles) by the end of the first day.
According to the report, the Iraqi army and Shia militias advancing from the south faced tougher opposition and more difficult terrain than the Peshmerga.
Along with the US, the British and French special forces are playing a supportive role in the operation.