In an interview on ABC's "This Week," Homeland Security Secretary Alejandro Mayorkas warned of a "very difficult threat landscape" after the New Orleans truck attack.

The New Orleans attack that killed 14 is thought to be the deadliest IS-inspired assault on U.S. soil since a 2016 massacre of 49 people inside Pulse, gay nightclub in Orlando, Florida.

He said the Bourbon Street attack was part of "a significant increase in what we term homegrown violent extremism."