Backed by U.S. coalition airstrikes, Kurdish Peshmerga forces in Iraq are advancing on ISIS-held Mosul.
Their operation began around 5:30 a.m Sunday.
Kurdish fighters say they've retaken five villages east of Mosul.
Recapturing Mosul would represent a major victory in the fight against ISIS. It's Iraq's second largest city and has been under ISIS control since June 2014. It was there that ISIS leader Abu Bakr al-Baghdadi declared a new "Islamic caliphate."
The Iraqi government has said it plans to take back Mosul by the end of the year. Already, it's made major progress.
The terrorist organization controls less than 10 percent of Iraqi territory, down from 40 percent at its peak, according to the country's defense minister.
The Associated Press contributed to this report.