There have been a few weapons that actually changed warfare. Tanks, Aircraft, Chlorine Gas, the machine gun, drones, atomic bombs are just some of the more significant.
The atomic bomb became more of a political weapon than a military weapon. The concept of mutually assured destruction has kept the atomic bomb as a mutual threat and negotiating tool. Neither side ever evolved a first strike capability that was quick enough to destroy the enemy without him having the time to strike back.
Hypersonic weapons represent a sea change in weapon development and could give an adversary the opportunity for a first strike with impunity.
It’s not just us that is developing this capability. Read more here.