Most of the above posts concern actions of one or another of the agencies overseen by DHS, Department of Homeland Security.

The DHS oversees and combines the actions of 22 government agencies.
The reorganization and combination of government agencies is a major change from the days of the National Security Act (NSA) of 1947.

The purpose is safe-guarding the United States and its territories from terrorist acts, both from abroad and internally.

In order to carry out its responsibilities, whatever is deemed necessary to ensure protection is done.
Surveillance at home and abroad is a key part of the protective measures. This includes all communications.

Congressional action to form and empower the DHS was necessitated by the strike on the Trade Center on Sept. 11, 2001, and terrorist actions against U. S. installations and personnel abroad.