Answer:
Mutual Assured Destruction
Step-by-step explanation:
President Ronal Reagan was unhappy with the Mutual Assured Destruction. Because of that, he announced the Strategic Defense Initiative. This SDI shifted US policy under nuclear weapons.
The MAD policy defended an uneasy peace during the Cold War because neither the US or the USSR attacked the other because they knew there should be nuclear retaliation.
Instead, the SDI used space-based lasers, particle beams, and other weapons staged in space.