One would have to dig a long way through the annals of espionage - both fiction and non-fiction - to find a tale quite as extraordinary as that of Pham Xuan An.
His achievements as a spy are merely one aspect of the story. Spying for then-North Vietnam in its long struggle against the American-backed South, An infiltrated the US and Vietnamese military, intelligence and journalistic establishments. His information and assessments for Hanoi shaped the war and its key battles, from its earliest days to its dramatic end in 1975.
A skilled charmer, his easy manner won him access to figures that included William Colby, chief of the CIA's Saigon station. Shortly after secretly joining the Vietnamese Communist Party in the mid-1950s, it was another CIA Asian veteran and presidential adviser, Edward Lansdale, who helped An with his big break: the chance to study journalism in California.
Equipped with reporting talent and a warmth and understanding towards the Americans and their culture, An spent much of the later part of the war as a staff correspondent for Time magazine - the only Vietnamese to reach such a position in the American press. As dozens of leading American reporters flocked to his side for crumbs of insight over coffee in Saigon's Cafe Givral, An was working for Hanoi, feeding covert reports to handlers hidden in under- ground tunnels in Cu Chi, outside Saigon.
But there's another side to the tale. As stories of An's real work and betrayals grew in the years after the war, remarkably so did understanding and tolerance of his actions in the minds of many former American and South Vietnamese colleagues and sources, including such celebrated reporter-authors as David Halberstam and Neil Sheehan.
In 2003, towards the end of his life, An was even invited by the US consul-general in Ho Chi Minh City aboard the USS Vandegrift, the first US warship to visit since the fall of Saigon.