Strategic Defense Initiative: President Ronald Reagan makes his initial proposal to develop technology to intercept enemy missiles.

The Strategic Defense Initiative (SDI), derisively nicknamed the Star Wars program, was a proposed missile defense system intended to protect the United States from attack by ballistic nuclear missiles. The program was announced in 1983 by President Ronald Reagan, a vocal critic of the doctrine of mutual assured destruction (MAD), which he described as a "suicide pact". Reagan called for a system that would end MAD and render nuclear weapons obsolete. Elements of the program reemerged in 2019 under the Space Development Agency (SDA).

Ronald Wilson Reagan was an American politician and actor who served as the 40th president of the United States from 1981 to 1989. A member of the Republican Party, he became an important figure in the American conservative movement. The period encompassing his presidency is known as the Reagan era.