"Probably what pushed the Russians over the edge was SDI. They realized they couldn't beat us"

This quote by Tom Clancy is referring to the Strategic Defense Initiative (SDI), a program proposed by President Ronald Reagan in 1983. The program was developed to produce a space-based missile defense system that would safeguard the United States from a nuclear attack. The Russians were concerned that the SDI would provide the United States a benefit in the Cold War, and they were not able to match the technological abilities of the program. This realization pressed the Russians over the edge, and they realized that they might not take on the United States in terms of military power. The SDI program was ultimately unsuccessful, but it was a significant consider completion of the Cold War. The Russians' realization that they might not beat the United States in regards to military power was a major consider completion of the Cold War.