Staff Sergeant Soto was a veteran of World War II. In Korea, he was the tail gunner of a B-26B Invader bomber with the 728th Bomber Squadron, 452nd Bomber Wing. On 1 July 1951, while on a night intruder mission, his aircraft was shot down over the southern end of Wanson Harbor, North Korea. He was listed as Missing in Action and was presumed dead on 31 December 1953. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Soto was awarded the Air Medal with 8 Oak Leaf Clusters, the Purple Heart, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation, the Republic of Korea War Service Medal and the World War II Victory Medal.