It’s a more extensive use of the app than previously reported and sheds new light on how commonly the Trump administration’s national security team relies on Signal.

The team led by U.S. President Donald Trump's national security adviser, Mike Waltz, set up at least 20 group chats on the commercial Signal app to coordinate official work on issues involving China,

The national security adviser's use of the messaging app is under scrutiny after he mistakenly added a journalist to a sensitive chat.