In 1954, America entered into a messy war to support South Vietnam against the communist regime in North Vietnam and its allies in southern Vietnam, known as the Viet Cong.
The two-decade long war claimed the lives of more than 3 million people, with the majority of the casualties being Vietnamese civilians.
In honour of the 40th anniversary of the end of the Vietnam War, here are some of the most gripping and recognisable photos from the conflict.
Editors note: Some of the following images are graphic in nature and may be disturbing to viewers.
In what might be the most enduring image from the war, a South Vietnamese general executes a suspected Viet Cong fighter in Saigon. The image won a Pulitzer Prize, but the photographer, Eddie Adams, dealt with an enduring sense of guilt over the photo.
In another of the war's most iconic photos, a 9-year-old girl is seen running naked from a napalm attack. This photo, by photographer Nick Ut, also won a Pulitzer Prize.
Source: Associated Press
In this photo, American paratroopers launch themselves into the largest ground-air assault in the war.
Ammunition is transported along the infamous Ho Chi Minh trail, a Viet Cong smuggling route which ran the length of Vietnam and allowed the North to transport weapons to communist guerrillas.
Source: The Guardian
Much of the war was fought in the jungle. Here, a US Army sergeant watches for Viet Cong snipers from an outpost near Saigon.
In this photo a soldier helps guide a Medevac helicopter through jungle foliage to pick up casualties suffered during a five-day patrol near Hue.
The body of an American paratrooper killed near the Cambodian border is seen being raised up to an evacuation helicopter. The US lost 58,220 soldiers during the Vietnam War.
This child soldier, captured in a photo by war photographer Philip Jones Griffiths, reportedly killed two Viet Cong women. He was nicknamed 'The Little Tiger.'
Children suffered greatly in Vietnam. In this photo, by well-known German photojournalist Horst Faas, South Vietnamese troops stare down at a father carrying the body of his child, who was killed in a fight against guerrillas in a village near the Cambodian border.
Children also witnessed horrific violence in Vietnam. In this photo, children on their way home from school pass the bodies of dead Viet Cong soldiers.
In another photo by Faas, this Vietnamese litter bearer, responsible for helping deal with a mass-casualty situation, wears a face mask to keep the smell of dead bodies from overwhelming him. These US and Vietnamese soldiers were killed while fighting the Viet Cong near Saigon.
In January 1968, the People's Army of North Vietnam bombarded the US Marine garrison at Khe Sanh in South Vietnam. The siege lasted 77 days and was one of the longest and most gruesome battles in the war.
US Army helicopters fire into the trees to provide air cover for South Vietnamese troops on the ground as they attack a Viet Cong camp near the Cambodian border.
An American prisoner of war is show greeting his family after his release. The war in Vietnam officially ended on April 30, 1975.
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