US INTELLIGENCE AGENCIES face a difficult task. They are supposed to provide meaningful analysis that enables officials to manage serious national security problems such as terrorism, weapons proliferation, network attacks on government infrastructure, and counterintelligence efforts. Today these are diffuse and complex threats. There are newly powerful political actors on the international stage. Organizations that are not governments and have no physical territory can inflict great harm. And individuals and diffuse coalitions are increasingly able to traffic in military technology, digital viruses, and other dangerous, potentially lethal tools. These challenges are real, and overcoming them are legitimate goals of foreign intelligence surveillance.
https://www.wired.com/2017/03/mass-spying-isnt-just-intrusive-ineffective/