We didn't have the technology to allow for surgical strikes in WWII that we do now. That being said, I am still of the opinion that the use of nuclear weapons against Japan was not as necessary as the US government led us to believe. The US crossed a line back then as well.
I won't go into detail here. If you're interested, look up the plans of the Soviet Union to invade Japan in August of 1945, which the US knew about, and the timing of that invasion compared to the timing of the Hiroshima bomb.