Public Law 84–104

That, under such regulations as the Secretary of State may prescribe, security officers of the Department of State and the Foreign Service who have been designated by the Secretary of State and who have qualified for the use of firearms, are authorized to carry firearms for the purpose of protecting heads of foreign states, high officials of foreign governments and other distinguished visitors to the United States, the Secretary of State, and the Under Secretary of State, and official representatives of foreign governments and of the United States attending international conferences, or performing special missions.