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.

Homeland Security Secretary Alejandro Mayorkas argued it is “not fair” to say that the city of New Orleans ignored the bulletin on the risks of attacks by drivers plowing cars into crowds of

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