Department of Homeland Security Secretary Alejandro Mayorkas said Thursday the United States won’t allow an "atmosphere of fear" to prevail after a deadly terror attack in New Orleans on Wednesday killed 14 people and injured dozens more.

CNN ’s Wolf Blitzer on Thursday asked Homeland Security Secretary Alejandro Mayorkas about memos where his department reportedly warned law enforcement agencies of “lone offenders” and the potential use of vehicle ramming about a month before the New Year’s Day attack in New Orleans.

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.