Brilliant Pebbles was a ballistic missile defense (BMD) system proposed by Lowell Wood and Edward Teller of the Lawrence Livermore National Laboratory (LLNL) in 1987, near the end of the Cold War. The system would consist of thousands of small satellites, each with missiles similar to conventional heat seeking missiles, placed in low Earth orbit constellations so that hundreds would be above the Soviet Union at all times. If the Soviets launched its ICBM fleet, the pebbles would detect their rocket motors using infrared seekers and collide with them. Because the pebble strikes the ICBM before the latter could release its warheads, each pebble could destroy several warheads with one shot.

The Strategic Defense Initiative (SDI), nicknamed the Star Wars program, was a proposed missile defense system intended to protect the US from attack by ballistic strategic nuclear weapons. The concept was announced in 1983, by President Ronald Reagan, a critic of the doctrine of mutual assured destruction (MAD), which he described as a "suicide pact". Reagan called upon American scientists and engineers to develop a system that would render nuclear weapons obsolete. Elements of the program reemerged in 2019 with the Space Development Agency (SDA).