Photo appears to show now-former national security advisor Mike Waltz checking Signal during a Cabinet meeting

On Wednesday, before news of his ouster broke, now-former national security advisor Mike Waltz was photographed during a Cabinet meeting looking at what appeared to be the encrypted messaging app, Signal.

He was a key player in a Signal snafu in President Donald Trump‘s second administration, referred to online and in some media coverage as “Signalgate.” The Atlantic’s editor in chief was inadvertently included in a sensitive defense conversation about military action in Yemen being conducted in a group chat through the app.

Trump announced Waltz’s ouster via social media on Thursday.

Trump plans to nominate Waltz as the next United States Ambassador to the United Nations, according to a post the president shared on Truth Social, adding that Waltz has “worked hard to put our Nation’s Interests first” and will continue to do so in his new role.

Secretary of State Marco Rubio will now also be acting national security advisor.

Waltz, a former Army Special Forces soldier, previously represented Florida’s 6th congressional district from 2019 to 2025 before becoming Trump’s national security advisor in January.

In a photo of Thursday’s cabinet meeting, a contact with the name of Vice President JD Vance and portions of a message were visible, as were additional message threads. Although the view of the content was obstructed, the last names “Rubio,” “Witkoff,” and “Gabbard” were visible, potentially referencing the Secretary of State, United States Special Envoy to the Middle East Steve Witkoff, and United States Director of National Intelligence Tulsi Gabbard.

Representatives for Rubio, Witkoff, and Gabbard did not immediately respond to requests for comment from Business Insider.

The bottom of Waltz’s phone’s screen displays a message that looks like Signal’s typical PIN verification message, but instead, the message displayed asks Waltz to verify his “TM SGNL PIN.” The “TM SGNL PIN” message is displayed on an unofficial — and less secure — version of Signal created by a company called TeleMessage, which makes clones of popular messaging apps, but enables the ability to archive messages, 404 Media and The Washington Post reported.

Trump, in an interview with The Atlantic published on Monday, said, “I would frankly tell these people not to use Signal.” The outlet’s editor in chief, Jeffrey Goldberg, said last month that he had been inadvertently added by Waltz to a group chat on the app.

The Signal group chat Goldberg says he was added to, called “Houthi PC small group” contained other officials, including Secretary of Defense Pete Hegseth, and included discussion of details of a planned US strike on Houthi rebels.

Business Insider previously reported that a former Pentagon spokesperson described the Signal incident involving Goldberg as causing a “full-blown meltdown” at the Pentagon, and “a real problem for the administration.”

However, despite widespread public criticism, Waltz and some other administration officials still appear to be using the app.

“As we have said many times, Signal is an approved app for government use and is loaded on government phones,” White House Deputy Press Secretary Anna Kelly told Business Insider of Waltz’s use of the app.

A spokesperson for Vance did not immediately respond to a request for comment from Business Insider.

Under President Joe Biden’s administration in 2024, the Cybersecurity and Infrastructure Security Agency (CISA) released a guide “for all audiences” outlining the best practices for secure personal communications amid a cybersecurity attack linked to the Chinese government. The CISA guide included Signal as an option for safer personal messaging.

However, guidance released by the Department of Defense during the Biden administration explicitly said that unmanaged messaging apps, including Signal, “are not authorized to access, transmit, process non-public DoD information.”

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