Vietnamese forces had surrounded the South Vietnamese capital of Saigon. The U.S. launched Operation Frequent Wind, sending U.S. Navy Task Force 76 to evacuate Saigon before North Vietnamese forces could capture the city, initially only to evacuate American embassy staff but eventually accepting South Vietnamese civilians and military personnel as they boarded evacuation flights or flew their own aircraft to the evacuation fleets, to the point that aircraft that were not being used had to be pushed off aircraft carriers to make space for more. In Operation Frequent Wind, a total of 1,373 Americans and 5,595 Vietnamese and third-country nationals were evacuated by helicopter, and the total number of Vietnamese evacuated by Frequent Wind or self-evacuated and ending up in the custody of the United States for processing as refugees to enter the United States totaled 138,869. Shortly after, North Vietnamese forces captured Saigon, ending the Vietnam War with a decisive North Vietnamese victory and initiating the reunification of Vietnam into the modern Socialist Republic of Vietnam. Saigon was renamed to Ho Chi Minh City, but the capital of Vietnam remained in Hanoi. Agent Orange "Agent Orange" was a herbicide and defoliant used by the U.S. as part of Operation Ranch Hand, a herbicidal warfare program initiated by the U.S. military. Developed from 1962 to 1971, Agent Orange consists of a fifty-fifty mixture of 2,4,5-T and 2,4-D, over 20 million gallons of it were produced by the U.S. over the course of the war. Agent Orange was primarily intended to destroy the foliage used as concealment by North Vietnamese soldiers. The 2,4,5-T used to produce Agent Orange was later discovered to be contaminated with 2,3,7,8-Tetrachlorodibenzodioxin, an extremely toxic dioxin compound. Agent Orange's use led to the deaths of thousands of people, the destruction of over 3.1 million hectares (31,000 km2 or 11,969 mi2) of Vietnam's forests, and up to a million Vietnamese and Americans alike experiencing birth defects, disabilities, and health problems resulting from the toxic chemicals used in Agent Orange. The Viet Nam Red Cross Society estimates that up to 1 million people are disabled or have health problems due to the effects of Agent Orange, but the U.S. government has dismissed these figures as unreliable and unrealistically high. Prisoners of war and missing soldiers Following American withdrawal from the Vietnam War in 1973, the U.S. listed about 2,500 Americans as prisoners of war (POW) or missing in action