Former national security adviser Mike Waltz defended his use of the messaging app Signal during a confirmation hearing Tuesday during which lawmakers largely avoided the topic.

The lawmakers used Waltz's nomination hearing for U.N. ambassador to resurrect criticisms of the handling of sensitive Signal chats.

Sen. Cory Booker, D-NJ, criticized Waltz’s inability to take accountability. Booker said Waltz “denied” and “deflected” rather than own up to his mistakes, something the New Jersey senator said is a “failure of leadership.” He called Waltz’s actions a show of “profound cowardice.”

President Donald Trump's former national security advisor Mike Waltz on Tuesday defiantly defended his use of a group chat to discuss military plans as he faced accusations of lying during a hearing to be US ambassador to the United Nations.