Defense Secretary Robert M. Gates and U.S. Navy Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, testify.

Assessment is the process of measuring, documenting, analyzing, and judging the results of executing a policy. Assessments can also be performed to analyze a perceived change in the strategic environment. Assessment often produces recommendations for change in current policy or the manner in which policy is implemented or executed.

There are many players that perform assessments. One of the best known forms of assessment is a Presidentially or Congressionally established commission. Examples of this type of assessment include the 9/11 Commission, the Baker-Hamilton Commission (also known as the Iraq Study Group), and the Tower Commission. The President also uses White House staff, particularly the Office of Management and Budget and the National Security Council staff, to evaluate policy, implementation efforts, and the results of execution. More informally, the President also receives feedback from outside experts (individuals or organizations), the media, and foreign leaders.

Congress has a strong assessment role and uses the Government Accountability Office, the Congressional Research Service, the Congressional Budget Office, committee staff, and hearings to produce assessments on national security issues. 

Internally, departments and agencies also perform many types of assessments.  At the broadest level, each agency is required by the Government Performance and Results Act of 1993 to produce program performance reports that evaluate achievements against objectives.  Agencies assess both the results of execution (outcome) and the effectiveness of implementation (output).

To perform assessment it is helpful to have clearly identified policy objectives, relevant and complete metrics and data, and an independent viewpoint.  Using assessments requires striking a balance between flexibility and accountability—knowing when to change the policy outcomes sought and knowing when to hold implementers and executers accountable.