The US Army Air Force dropped atomic bombs on the two Japanese cities, as ordered by then-President of the US, Harry S. Truman. During the final stages of World War II in 194 … 5, the US conducted two atomic bombings against Japan, on the cities of Hiroshima and Nagasaki.aking Japan surrender to end World War 2 was the only pro to the bombing. The main cons are that 135,000 of mostly civilians died as a result, and in particular, the second bomb was probably not even necessary.