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An encrypted messaging app called Signal is drawing attention and questions after top Trump officials — including Defense Secretary Pete Hegseth and Vice President JD Vance — allegedly used the service to discuss a highly sensitive military operation while inadvertently including The Atlantic’s editor-in-chief, Jeffrey Goldberg, in the chat.
On Monday, Goldberg published a piece in The Atlantic about how he was added to an 18-person chat on Signal earlier this month to discuss military strikes in Yemen, writing that at first he “didn’t think it could be real.”
The National Security Council said the messages seem to be “authentic,” in a statement to CBS News after the story was published.
The use of Signal to discuss sensitive military operations is raising questions about the app, including its level of security against hackers and other bad actors. It’s an app that many Americans may not be familiar with, given that Signal had about 70 million users in 2024, a fraction of the 1 billion active monthly users of Apple’s iMessage, according to the national security publication Lawfare.
President Trump told reporters on Tuesday that he had asked national security adviser Mike Waltz, who Goldberg said added him to the group chat, to “immediately study” the use of Signal by government officials.
Here’s what to know about the service.
What is Signal?
Signal is an encrypted service for text messaging, but it can also handle phone and video calls, making it a versatile app for talking on a secure channel with others. Up to 1,000 people can join a group chat, and messages can be set to disappear after a period of time.
Signal has been gaining users because of its end-to-end encryption, which is boosting its “adoption during uncertain times or specific events which reinforce its position as the go-to communication service,” PP Foresight analyst Paolo Pescatore told CBS MoneyWatch.
Its encryption prevents any third-party from viewing conversation content or listening in on calls. In other words, messages and calls sent on Signal are scrambled and only the sender and recipient at each end will have the key to decipher them.
Unlike another popular messaging app, Telegram, encryption on Signal is turned on by default. Signal also says it doesn’t collect or store any sensitive information.
“Signal messages and calls cannot be accessed by us or other third parties because they are always end-to-end encrypted, private and secure,” according to the service.
Signal didn’t immediately reply to a request for comment about the Trump administration’s use of the app.
Who owns Signal?
Signal is owned by the nonprofit Signal Foundation, which was set up by co-founders Moxie Marlinspike and Brian Acton to support the app’s operations as well as “investigate the future of private communication,” according to the foundation’s website. The foundation says it is a nonprofit “with no advertisers or investors, sustained only by the people who use and value it.”
The foundation’s board has five members, including Marlinspike and Acton, who co-founded WhatsApp and donated $50 million to set up the foundation.
The Signal app was created more than a decade ago by Marlinspike, an entrepreneur, who was briefly head of product security at Twitter after he sold his mobile security startup, called Whisper Systems, to the social media company in 2011. Marlinspike merged two existing open source apps, one for texting and one for voice calls, to create Signal.
Can Signal be hacked?
Signal touts the privacy of its service, and experts agree it is more secure than conventional texting.
But they also caution that it could be hacked. And in February 2025, the National Security Agency sent out an operational security special bulletin to its employees cautioning them of vulnerabilities in the Signal app, according to internal NSA documents obtained by CBS News.
“A vulnerability has been identified in the Signal Messenger Application. The use of Signal by common targets of surveillance and espionage activity has made the application a high value target to intercept sensitive information,” the internal bulletin says.
Government officials have used Signal for organizational correspondence, such as scheduling sensitive meetings. But in the Biden administration, people who had permission to download it on their White House-issued phones were instructed to use the app sparingly, according to a former national security official who served in the administration.
“Unlike other end-to-end encryption messaging services, Signal does boast a rich range of features,” Pescatore said. “However, hackers are always on the prowl to find weaknesses and use apps maliciously.”
What is Signal typically used for?
Because of its end-to-end encryption, Signal is often used by national security and intelligence professionals, as well as activists, among others, according to Lawfare.
A recent Associated Press review found that encrypted messaging apps are increasingly popular with government officials, with some using government mobile phone numbers, while others registered their accounts to personal numbers.
Are there legal issues for government officials using Signal?
Possibly, yes. Sharing sensitive national security details over Signal could violate the Espionage Act, CBS News national security contributor Sam Vinograd, who served in former President Barack Obama’s Homeland Security Department, said Tuesday.
“By communicating classified information on a nonsecure platform like Signal, senior U.S. government officials … increased the chance that foreign governments could get access to sensitive operational security plans — and that could put our own troops in harm’s way,” Vinograd said.
While Mr. Trump told reporters from the Oval Office on Tuesday that “I don’t know anything about Signal, I wasn’t involved in this,” he indicated that other branches of government use the app.
“I hear it’s used by a lot of groups, I hear it’s used by the media a lot,” he said. “A lot of the military, I think successfully. Sometimes people can get onto those things, that’s one of the prices you pay when you’re not sitting in the Situation Room with no phones, which is always the best, frankly. The best is to be there.”
Mr. Trump said Signal is the “No. 1 device or app that is used” that he had asked Waltz to explore its use by government officials.
Meanwhile, Democratic lawmakers are demanding an investigation into why highly sensitive information was being discussed on a commercially available messaging app, rather than secure government channels.
The Atlantic’s Goldberg also alleged that some of the messages in the group chat were designed to disappear after one week, and others after four weeks, which could be a violation of federal law requiring the preservation of official records.
contributed to this report.
