The White House, Executive Order 13407, Public Alert and Warning System (June 26, 2006) (full-text), amended by Executive Order 13414.
This Executive Order established as policy the requirement for the United States to have an effective, reliable, integrated, flexible, and comprehensive system to alert and warn the American people. It assigns the Secretary of Homeland Security the responsibility to establish or adopt, as appropriate, common alerting and warning protocols, standards, terminology, and operating procedures for the public alert and warning system to enable interoperability and the secure delivery of coordinated messages to the American people, taking account of Federal Communications Commission rules as provided by law.
FEMA is designated within the Department of Homeland Security to implement the public alert and warning system as outlined in this Executive Order and has established a program office to implement the Integrated Public Alert and Warning System (IPAWS).
FEMA and its federal partners, the Federal Communications Commission, the National Oceanic and Atmospheric Administration's National Weather Service and the DHS Science and Technology Directorate are working together to transform the national alert and warning system to enable rapid dissemination of authenticated alert information over as many communications channels as possible.