On 9 May 2007, the Bush White House issued National Security Presidential Directive 51 / Homeland Security Presidential Directive 20. The joint directive "establishes a comprehensive national policy on the continuity of Federal Government structures and operations and a single National Continuity Coordinator responsible for coordinating the development and implementation of Federal continuity policies."

In a related move, on 8 October 2001, President Bush released an Executive Order Establishing Office of Homeland Security that amended Executive Order 12656 (November 1988).

This current Bush executive order supersedes the Clinton-era COOP executive order, Presidential Decision Directive 67 ("Enduring Constitutional Government and Continuity of Government Operations"), which was issued on 21 October 1998.

It also demonstrates a marked departure from prior nuclear concerns, according to the Washington Post:

• The order makes explicit that the focus of federal worst-case planning involves a covert nuclear attack against the nation's capital, in contrast with Cold War assumptions that a long-range strike would be preceded by a notice of minutes or hours as missiles were fueled and launched.

The Clinton White House did not release the text or summary of PDD-67. Like the Bush replacement as well as its predecessors, this directive required Federal agencies to develop Continuity of Operations Plans for Essential Operations.

The only public document relating to that executive order is a Federal Preparedness Circular (FPC-65) that provides guidance to Federal Executive Branch departments and agencies as they develop contingency plans for the continuity of operations (COOP).

It is similar to the 2004 FEMA directive.

Clinton's declaration replaced the first Bush Administration's NSD 69 "Enduring Constitutional Government" of 02 June 1992, which in turn replaced NSD 37 "Enduring Constitutional Government" of 18 April 1990 and NSDD 55 "Enduring National Leadership" of 14 September 1982, according to the FAS.

In addition, 18 Executive Order 12656 (Section 202, 18 November 1988) required that "[t]he head of each Federal department and agency shall ensure the continuity of essential functions in any national security emergency by providing for: succession to office and emergency delegation of authority in accordance with applicable law; safekeeping of essential resources, facilities, and records; and establishment of emergency operating capabilities." It revoked Executive Order 10421 of 31 December 1952.

Reagan charged the Federal Emergency Management Agency (FEMA) with coordinating and implementing these plans.

In addition, Reagan established the National Communications System (NCS), via Executive ORder 12472 (1984), "in order to provide for the consolidation of assignment and responsibility for improved execution of national security and emergency preparedness telecommunications functions."

President Carter established FEMA via Executive Order 12148 on 20 July 1979. [On 1 March 2003, FEMA became part of the Department of Homeland Security's Emergency Preparedness and Response Directorate.]

The National Security Act of 1947, signed into law by President Truman, merged the Department of War and the Department of the Navy, created the Department of the Air Force, established the National Security Council and the Central Intelligence Agency.

Also in 1947, the Presidential Succession Act established a line of succession if the Vice President dies or cannot serve. (The law picks up where the Constitution leaves off.)
First, the speaker of the House of Representatives would become President. Next: the president pro tempore of the Senate followed by members of the Cabinet, in the order in which their posts were created.