"We've set the conditions for ISIS 2.0 ... and we're repeating the mistakes of the Obama administration, which pulled out of Iraq too soon and led to all of this in the first place, except we won't have any local allies to fight them again," Michael Waltz said.
Thousands of ISIS fighters are being held by Kurdish-led forces in northeastern Syria, but the Turkish assault threatens the security of the detention centers there.
Some militants are still fighting while others are "hiding out in sympathetic communities and urban areas," according to a new U.N. report.
A man believed to have helped oversee the creation of ISIS's global caliphate says he hasn't seen Abu Bakr al-Baghdadi since July 2017.
ISIS leader Abu Bakr al-Baghdadi once laid claim to half of Iraq and Syria, but now only a small, mostly desert stretch known as Al-Jazeera, or "the Island," remains.
It includes the militants' elusive leader Abu Bakr al-Baghdadi as well as his second-in-command.
The newspaper is seeking an apology as Trump's claim the paper leaked information becomes his latest attack on the press.
Russia is still not sure whether its military killed ISIS leader Abu Bakr al-Baghdadi.
Two Syrian activist groups with ties to the country's opposition also offered opposing claims about the Islamic State militant group leader's death.
A representative to one of Iran's most elite fighting forces has confirmed the death of Islamic State militant group leader Abu Bakr al-Baghdadi
Jack Letts traveled to Syria but says he is against ISIS and its ideology.
The self-proclaimed caliph, in his first audio message in a year, also called for attacks.
ISIS is also increasingly active in Afghanistan.
Kurdish-led forces launch offensive north of Raqqa against the radical Islamist group.
The radical Islamist group has retained a presence around the ancient Syrian city as clashes continue.