Shamsud Din Jabbar, 42, served in the Army on active duty from 2006 to 2015 and was deployed to Afghanistan in 2009, according to three U.S. defense officials.

A U.S. Army veteran who drove a pickup truck into a crowd of New Year’s revelers in New Orleans, killing 15 people, had posted videos to social media hours before the carnage saying he was inspired by the Islamic State group and expressing a desire to kill.