The New Orleans mass killing put a spotlight back on ISIS, which never really went away

Iraqi troops enter a town seized from ISIS militants in 2017.

AHMAD AL-RUBAYE/AFP via Getty Images

• The New Orleans attack suspect carried an ISIS flag and pledged fealty to the group, officials said.
• The group, best known for global mass killings in 2015-2017, has again been gathering strength.
• The group was damaged but not defeated by a US-led campaign.

Back in 2017, the ISIS militant group's reign of terror appeared to be coming to an end.

A US-led...