How might the resistance at Iwo Jima and Okinawa have affected American leaders decisions during the final stages of war?

"The experiences by the United States Military in taking the key locations of Iwo Jima and Okinawa affected the future of the war due to the casualties sustained. The Japanesse fought so hard and with such fury even in the face of certain death that the United States wanted to avoid a mainland invasion of Japan. The battles that were waged on these islands showed that the Japanesse military would fight to certain death, and with Japan refusing to surrender when they had been pushed back to their home island also influenced the United States to eventually use to Nuclear weapons on Japan."