That was is definitely the easiest question, Japan made an attack on us, they bombed Pearl Harbor, it was unexpected and lives were lost, so, we had to do something about it, so in response we made a powerful weapon, during the process of it, it was called the Manhattan Project, though it wasn't in Manhattan, we warned Japan's government that we had powerful weapons and we would use them on the Japanese if they didn't back out of the war, well, Japan didn't, so we dropped an atomic bomb on them, when they still didn't back out, we hit them again. This was how we got involved in it all.