Examine the map of Allied advances in the Pacific theater. A map of Allied advances in the Pacific theater. Countries labeled are the U S S R, Mongolia, Manchuria, Korea, Japan, Taiwan, China, Burma, Thailand, Malaya, Dutch East Indies, New Guinea, Philippines, and Iwo Jima. Japanese territory is highlighted. Allies are China, Mongolia, U S S R, and New Guinea. The extent of Japanese expansion is noted by a dotted line. Allied advances are shown as arrows. The allied advanced from New Guinea to the Philippines and Taiwan. Another advance went from Iwo Jima past the western coast of Japan. Based on the map, which reason convinced the US to attack the island of Iwo Jima? Its location made it useful as a base for air attacks on Japan. Its location was important to the defense of the US mainland. Its location was important for stopping Japanese attacks on Australia. Its location made it essential for launching a ground invasion of Japan.