The development of nuclear weapons was a human stupidity. They cannot be used, but their existence threatens the life of the planet.  So why have them?  Accident, emotional response, loss of reason are all human faults that can come into play at any time.  

During the 20th century Cold War these dangers were underlined by the Cuban Missile Crisis.  President Nixon led the way to sanity with arms control agreements with the Soviet Union and his opening to China. Presidents Carter and Reagan kept the momentum going for reduced tensions and peaceful coexistence.  

The turnaround came with the Soviet collapse.  The neoconservatives took advantage of Russian weakness and prevailed on President Clinton to break the promise given by the George H.W. Bush administration to Gorbachev not to move NATO to Soviet borders if Gorbachev permitted the reunification of Germany.  The George W. Bush and Obama administrations continued the hostile policy that Clinton renewed.