When the war ended in 1953, tens of thousands of Korean and Chinese prisoners of war chose life in the US over their own homelands.
But America, in the grip of anti-communist fervour, was shocked when 20 of its own young soldiers defected to China.
David Hawkins was just 17 years old when he was wounded in battle and captured. Held prisoner for more than three years, when the war ended he decided not to return home.
"My reasoning was, they really have embraced this socialism so let me see what it is like - let me check it out," says Mr Hawkins, now 78 and living in California.
After his capture a few months after arriving on the front in Korea, Mr Hawkins was taken to a prisoner-of-war camp run by the Chinese - the prisoners called it "Death Valley".
"This doctor handed me a little piece of shrapnel that he'd taken out of my leg and said: 'We are your friends, we won't hurt you,'" he says.
The compound was unheated, and at night, the temperature fell far below zero.
He and his comrades suffered severe frostbite. He lost a toe on his left foot and the tips of all of his other toes.
"We were all covered with lice by that time, we started to develop scabies," he remembers. "All of us had dysentery, we were all incontinent."
Within a week of arriving at the camp, American GIs began to die.
The intense cold meant those who survived did not have to worry about the bodies decomposing, and in order to trick the prison guards into providing more food rations, they would prop the corpses against the wall so that it appeared there were more people in the room.
"We were on a very thin line of survival," he says. "I was just 17. I turned 17 on the way over to Korea, so maybe that youth allowed me to survive."
More than 60 years later he is moved to tears as he recalls waking up and finding comrades dead beside him. He still suffers from nightmares.
Several months later the prisoners were moved to another camp where the conditions were far better. They had sports equipment, better food and washing facilities, but their Chinese captors also subjected the soldiers to six or seven hours of indoctrination per day.
The lectures on the glories of Marxism and the evils of capitalism had little effect.
"When we would get back to the squads we would all sit around and talk about cars and women and that sort of thing, like GIs do," he says.
The Americans were surprised at their mild treatment - they had been warned the Chinese were brutal and sadistic to their prisoners.
As Mr Hawkins languished in the camp and the fighting raged on between the US-led UN force and the North Koreans and Chinese, the two sides spent two years negotiating an armistice.
Free to leave
The chief sticking point was the fate of the hundreds of thousands of North Korean and Chinese prisoners held in the south.
The Geneva Conventions in effect at the time called for all prisoners of war to be returned home when fighting ended. But many North Korean and Chinese prisoners in the south refused to be sent north following the ceasefire, and the armistice signed in July 1953 allowed for prisoners from both sides who wanted to stay behind to do so.
When it came time for his release, Mr Hawkins says, he had been so impressed by the Chinese he opted to return with them to Beijing, where he enrolled in language courses at a university.
"The one thing that they'd always said is that you're not there forever, you can come home any time you want," he says.
"I never thought of the consequences, quite honestly, I was looking through a very narrow window of opportunity."
After university, he obtained a commercial driving licence and moved to the city of Wuhan. There he drove a Czechoslovakian truck for a factory. He was the only non-Chinese in the city, he says.
"People were not shy," he recalls. And he says people would treat him as a celebrity when they learned he was American.
"They wanted to know what your lifestyle was like and where you lived," he says.
But after three years, Mr Hawkins decided it was time to return home.
"That was the only time I was really nervous, was when I got back to the States," he says.
His wife, a Russian woman he married in Beijing, joined him a year later and the couple eventually had two children, but Mr Hawkins had a difficult time readjusting.
"My thought processes and everything were in Chinese," he says. "In China I was dealing with people much older than I, much more sophisticated politically and I found it very shallow. I couldn't deal with people on that level when I came back."
'A real patriot'
He was also surprised he faced no personal animosity when he returned. In fact, Mr Hawkins was sought by universities to lecture about his experience, and was even invited as a guest on TV news programmes such as The Mike Wallace Interview.
Nevertheless, the US Army gave him a dishonourable discharge and refused to pay him for the years he spent in combat and in the prison camps.
"I never had regrets," he says. "The one big thing I learnt about going to China was how lucky we are here in the US. Our government's not perfect but I think it's one of the best in the world.
"So I learnt so much, I learned to be a better American. If nothing else I'm a real patriot."
Chloe Hadjimatheou's interview with David Hawkins will be broadcast on BBC World Service Witness. You can download a podcast of the programme or browse the archive.
Korean War, 1950- 1953
- 1945: The Korean peninsula is split in half at the 38th Parallel following WWII, with a Soviet-backed Stalinist regime in the north and an American-backed regime in the south
- June 1950: North Korean troops under Kim Il Sung invade the south. Pushed by the US, the UN Security Council authorises a military response
- September - October 1950: The US-led military force pushes the North Korean army back over the 38th Parallel.
- November 1950: The Chinese invade from the north, driving the UN forces back to the south
- Spring 1951: The line settles near the 38th Parallel
- 1951 - 1953: For two years, the two sides pummel each other with heavy artillery and pursue costly infantry attacks across the lines, while US planes ground the North Korean air force and bomb the north
- July 1953: The two sides negotiate a ceasefire and thousands of prisoners from each side cross the newly drawn demilitarised zone on the border