Final answer:
The long-term consequence of the US use of atomic weapons during WWII was the start of the nuclear arms race between the US and the Soviet Union, leading to the development and stockpiling of massive nuclear arsenals.
Step-by-step explanation:
One of the long-term consequences of the US use of atomic weapons during WWII was the start of the nuclear arms race between the United States and the Soviet Union. After the US dropped atomic bombs on Hiroshima and Nagasaki, the Soviet Union developed their own atomic bomb in 1949, ending the US monopoly on nuclear weapons. This led to a period of intense competition as both countries stockpiled massive nuclear arsenals to maintain their military superiority.