British intelligence agency GCHQ is able to not just monitor, but also modify many of the worlds most widely-used communications services: Facebook, YouTube, and phone calls are just a few of the services affected. The Intercept revealed the documents today (which can be read here), continuing reporter Gleen Greenwalds year-plus of working with whistleblower Edward Snowden on exposing the clandestine surveillance tactics of the United States and Britain.