Encrypted messaging app Signal continues to see spiking downloads in the wake of the messaging scandal, which saw The Atlantic’s editor in chief Jeffrey Goldberg added to a group chat where high-ranking officials in the Trump administration were discussing an attack on Houthi rebels in Yemen. The resulting press coverage around the leak of these sensitive plans has been driving more people to check out Signal’s app for the first time, leading to a doubling of its downloads.

The White House has gone on the defensive, saying no classified information was shared in the chat. But NPR is now reporting that a Pentagon-wide advisory sent to staffers on March 18 — less than a week before the screwup went public — explicitly warned against using Signal for any sharing of information, classified or not.

The advisory claimed that a “vulnerability has been identified in the Signal messenger application,” and that Russian hacking groups were “targeting Signal Messenger to spy on persons of interest” (a Signal spokesperson told NPR that the company wasn’t “aware of any vulnerabilities or supposed ones that we haven’t addressed publicly.”)