History of the United States (1991–2008) South Tower less than twenty minutes later at 9:03 A.M. (EST), resulting in the collapse of both 110 story skyscrapers, and the destruction of the World Trade Center. The third hijacked plane, American Airlines Flight 77, was crashed into the Pentagon (the headquarters of the United States Department of Defense) in Arlington County, Virginia, demolishing a section of the outer southwest facing wall. After discovering that their plane, United Airlines Flight 93, was going to be used as a missile, passengers attempted to regain control of the plane which had been redirected towards Washington, D.C. However, after regaining control from
Chief Management Officer of the Department of Defense Chief Management Officer of the Department of Defense The Chief Management Officer (CMO) of the United States Department of Defense (DoD) is the third-in-command of the department after the Secretary of Defense and Deputy Secretary of Defense. The position's purpose is to reduce costs by improving the quality and productivity of DoD's business operations. The CMO's office contains six "reform leaders" in the areas of logistics and supply chains, real property, community services, human resources, and health care, and a Program Executive Officer for IT Business Systems. The office also oversees Washington Headquarters Services and Pentagon Force Protection Agency, and