U.S. government agencies are secretly tracking WhatsApp users without explanation or without knowing the target, Forbes reports. In an unsealed surveillance application, the U.S. Drug Enforcement Administration had WhatsApp monitor IP addresses associated with seven users in China and Macau under the 1986 Pen Register Act. The DEA mandated WhatsApp monitor who the targets communicated with and how they used the application. Over the last two years, U.S. law enforcement has repeatedly mandated WhatsApp and other technology companies to install pen registers without probable cause.