Signalgate was the national security adviser’s most glaring mistake. But his problems ran deeper. After Michael Waltz, the national security adviser, inadvertently included The Atlantic ’s editor in chief in a group chat about military attack plans on the Signal messaging app, he found himself on very thin ice with his boss.

Mike Waltz, the national security adviser for President Donald Trump, is seen in photos using Signal during a Cabinet meeting on April 30.

Reaction to Waltz’s ‘promotion,’ Rubio now ‘secretary of everything,’ Air Force nominee grilled, Trump wants Veterans Day renamed Victory Day for World War I.