Explain the arm race due to cold war?

1)       Though America and Russia were fighting against dictators jointly in the Second World War, America deliberately kept Russia in dark about its readiness in nuclear weapons, power, tools.
2)       After the Second World War, Russia also performed nuclear test and showed that it was also well prepared in nuclear arms.
3)       America and its alliance came together due to the treaty of Warsaw.
Cold war became severe because of this competition in weapons