Pentagon-wide email recently went out warning about Signal vulnerability

A Pentagon-wide advisory went out one week ago warning against using the messaging app Signal, even for unclassified information.

The memo continues, “Russian professional hacking groups are employing the ‘linked devices’ features to spy on encrypted conversations.” It notes that Google has identified Russian hacking groups who are “targeting Signal Messenger to spy on persons of interest.”

The encrypted Signal app is what Defense Secretary Pete Hegseth and other leading national security officials within the administration used to discuss bombing Houthi sites in Yemen earlier this month. The Atlantic editor Jeffrey Goldberg was inadvertently added to the group and privy to the highly sensitive discussions.

In the military, sending classified data over insecure channels is called “slippage” when it’s considered minor, but even that can be a career ender for a military officer.

There’s almost no precedent for the heads of Defense, State, Intelligence and National Security to be sharing such sensitive military intelligence in a forum that was known to be unsecured.