The revelation has rekindled the controversial debate over whether tech companies should implement backdoors that allow governments access to encrypted information on digital devices.
The UK's home secretary, Amber Rudd, threw down the gauntlet on the issue in an interview with the BBC. "We need to make sure that organizations like WhatsApp, and there are plenty of others like that, don't provide a secret place for terrorists to communicate with each other," Rudd said ahead of her upcoming meetings with several technology firms.
Last year, WhatsApp instituted end-to-end encryption across all of its communications. This essentially rendered all messages sent through the app unreadable by anyone other than the sender and recipient.
"No one can see inside that message," WhatsApp announced last year when unveiling the encryption update. "Not cybercriminals. Not hackers. Not oppressive regimes. Not even us."