Vietnam and the United States took the first step towards cleaning up Agent Orange contamination on Friday, a development that the top US diplomat in the country said was one of the most significant between the two countries.
A ribbon cutting near a barren, sun-baked corner of the Da Nang airport grounds where the defoliant was stored before being sprayed from US warplanes during the 1960s and early 70s held symbolic meaning for a relationship that has come under the spotlight amid renewed tensions in the South China Sea.
US-Vietnam ties have blossomed since diplomatic relations were established 16 years ago and steps to resolve legacy issues from the war have formed a cornerstone of progress.
"I think it's fair to say that dioxin contamination and Agent Orange was one of the single most neuralgic issues in the US-Vietnam relationship," said US Charge d'Affairs Virgina Palmer.
The US military sprayed up to 12 million gallons of the defoliant between 1961 and 1971 to try to make it easier to fight in Vietnam's dense jungles.
For years, Hanoi and Washington talked past each other on questions of compensation for Vietnamese with health problems that the Vietnamese government said resulted from exposure to Agent Orange.
But five years ago the embassy began to shift the focus to cleaning up dioxin hot spots, clearing the path for swift headway on what had become the biggest remaining war-era issue.
The US Congress appropriated an initial $3 million in 2007 for the effort and the figure has since leapt to $32 million. The progress has been "hugely important and has had very nice repercussions for the rest of the relationship", said Palmer.
Trade has galloped from almost nothing in the mid-1990s to $18 billion a year, mostly in the form of exports to America, which help keep Vietnam's trade deficit in check. Political and military ties are also improving and US Navy ships visit the former foe at least annually.