Why is this surprising? Everyone knows that had japan had nukes, they would have used them on The USA. Everyone knows that had we not used nukes on Japan, Japan still would have lost the war eventually. The nukes were used to end the war quickly.
If those bombs were not dropped, and with the information the United States had on Japan at the time, the United States was prepared to invade Japan at a cost of up to the lives of 1,000,000 American soldiers and millions of Japanese soldiers and civilians. Thousands of lives were lost at Hiroshima and Nagasaki so that millions were not.