Mike Waltz has come under scrutiny due to a photograph showing his use of a modified messaging application, TM SGNL, raising security concerns. The photo, taken by Reuters on April 30, 2025, during a White House cabinet meeting, revealed Waltz's phone screen with conversations involving JD Vance, Marco Rubio, Tulsi Gabbard, and Steve Witkoff, who are key figures in foreign relations and national security regarding Ukraine. TM SGNL is a variant of Signal, known for its encryption, but its archiving feature risks compromising end-to-end encryption. Messages displayed included a note to Rubio stating, "there is time," and Vance's message about confirmation from a counterpart. Following these events, President Trump appointed Waltz as UN ambassador and Rubio as interim national security advisor. The White House stated that "Signal is an approved app for government use and is loaded on government phones."