What nation held the edge in the arms race in late 1960?

In late 1960, the United States held the edge in the arms race, primarily due to its significant advancements in nuclear weapon technology and delivery systems, such as intercontinental ballistic missiles (ICBMs) and submarine-launched ballistic missiles (SLBMs). The U.S. had a more extensive nuclear arsenal compared to the Soviet Union at that time, which was still in the process of developing its own ICBM capabilities. However, the Soviet Union was rapidly advancing and would soon challenge the U.S. lead in the following years.