Immediately after world war ii, what key advantage did the united states have over the soviet union?

The United States had the atomic bombs while the Soviet Union had not developed one yet. The U.S had a large Navy, Marine Corp and Army and Air Force. The USSR did not have a large Navy or marine corp. The US had not killed off their engineers, scientists, manufacturers or builders as for the Soviet Union, Stalin had done so they could outdo the Soviet in new development.