When conscription was increased, some Puerto Ricans from the island were assigned as replacements to units in the Panama Canal Zone and British Caribbean islands, which were made up mostly of continental (United States mainland) soldiers. Most Puerto Ricans and Hispanics residing in Puerto Rico were assigned to the 65th Infantry Regiment or to the Puerto Rico National Guard. These were the only all-Hispanic units whose statistics were kept. Puerto Rican aviators were sent to the Tuskegee Army Air Field in Tuskegee, Alabama, to train the famed 99th Fighter Squadron of the Tuskegee Airmen. The Tuskegee Airmen was a segregated unit of African-Americans and Hispanics of African heritage. They were the first people of African heritage to become military aviators in the United States armed forces. More than 53,000 Puerto Ricans and Hispanics who resided on the island served in the war. According to Senator Robert Menendez, more than 9,000 Latinos died in the defense of the United States in World War II. Because of lack of separate documentation, the total number of Hispanic Americans who died in the conflict is unknown.