On June 18, 1878, Congress passed the Posse Comitatus Act. This law made it a felony to willfully use "any part of the Army...to execute the laws" except where expressly authorized by the Constitution or by an act of Congress.

Learn more about the origins of the Posse Comitatus.

On June 18, 1979, the United States and Soviet Union signed the SALT II nuclear arms limitation treaty. The treaty was part of a series of nuclear arms reduction treaties signed between the U.S. and U.S.S.R. SALT II was preceded by SALT I and followed by the Strategic Arms Reduction Treaty (START) and START II.

Learn more about arms reduction agreements between the U.S. and U.S.S.R. from the Nuclear Threat Initiative.