A defense contractor is a private company that provides products or services to governments to support military operations and national security. Companies typically bid for government contracts, in which the government sets the requirements and carries all the costs of research and development. There are currently 5 major American defense contractors, collectively known as “Big Defense”: Lockheed Martin, RTX, Boeing, Genera!Dynamics, and Northrop Grumman. These firms primarily contract with the US. Department of Defense (DoD), but they also have contracts with other governments.