No matter how you measure it, by aircraft, ships, or active-duty military personnel, the US Department of Defense (DoD) is big. Except for
, the Department of Defense -- comprising the
, Reserves, and more than a dozen defense agencies -- is the largest component of US government spending. The 2012 budget for the Department of Defense is more than $670 billion, 18% of which will be used to fund the ongoing military engagements in Afghanistan and Iraq. The DoD maintains a force of about 1.4 million active duty service members and operates thousands of facilities around the world.