US displayed its nuclear power in World War II forcing USSR to build a secret city that stayed off the maps for decades!

Startled U.S!

It came as a shock for the U.S. as the intelligence agency of the country was not expecting explosion for many more years. No doubt the development exacerbated the already strained relationship between U.S. and Soviet Union. The impact could easily be understood as both the company had made tremendous changes in their foreign policy.