In 1968, following the spree of political assassinations including: the assassination of John F. Kennedy, the assassination of Robert F. Kennedy, and the assassination of Martin Luther King Jr, President Lyndon B. Johnson, pushed Congress for the Gun Control Act of 1968 ("GCA"). It repealed and replaced the FFA, regulated “destructive devices” (such as bombs, mines, grenades, and other explosives), expanded the definition of machine gun, required the serialization of manufactured or imported guns, banned importing military style weapons, and imposed a 21 age minimum on the purchasing of handguns from FFLs. The GCA also prohibited selling of firearms to felons and the mentally ill.