In 2007, the Homeland Security Act of 2002 was amended to require the Department of Homeland Security (DHS) to initiate implementation of a Quadrennial Homeland Security Reviews (QHSR) in 2009, and to conduct subsequent reviews every four years thereafter. The purpose of the QHSR was to describe the threats to the national security interests of the Nation, outline and prioritize the full range of homeland security missions, and update the national homeland security strategy. It would also assess the alignment of the Department to the strategy, promote mechanisms for turning strategic requirements into an acquisition strategy and expenditure plan, and identify the budget plan for successfully executing the homeland security missions.