Four decades after the fall of Saigon the warm welcome afforded a Vietnamese Communist Party leader in the Oval Office appears to signal a new phase in relations between the two former enemies.
The presence of Nguyen Phu Trong in Washington indicates a growing sense of urgency on both sides as China steps up its claim on the disputed waters of the South China Sea.
Vietnam feels a growing need for American help in its efforts to counterbalance the perceived threat from its giant northern neighbour – even if it means supping with the devil.
The unsentimental words attributed to General De Gaulle – “Countries don’t have friends, they have interests” – might have been a fitting subtitle as Mr Trong sat down with President Obama.
The Vietnam Communist Party remains deeply suspicious of its old ideological enemies in Washington – even to the point of paranoia.
Diplomatic relations with the US were established 20 years ago and there have been many top-level state to state encounters since.
But the presence of the General-Secretary of the Communist Party at the White House takes the relationship to a new level.
He is supposed, after all, to be the guardian of ideological rectitude in these ambiguous times.
The party sees the subversive hand of the US everywhere as it tries to contain the challenge from a growing domestic network of civil society groups and human rights advocates.
So the decision by Mr Trong to enter the camp of the old enemy is a dramatic gesture that sends a strong message to Beijing.
The impact is accentuated by his reputation as a conservative who has devoted much attention to shoring up deteriorating relations with Beijing.
Mr Trong told reporters for western media before leaving Hanoi that the United States was a force for stability in the South China Sea – quite a statement for a successor to Ho Chi Minh.
Growing tensions with Beijing in the area have sent Vietnam scurrying for help wherever it can be found.
“Like in any relations between two countries in the world, Vietnam and the US have differences on a number of issues such as perception on democracy, human rights and trade,” Mr Trong said in his written reply to the journalists.
“To resolve differences, we should have be open and constructive dialogue to better understand each other so that differences won’t become hurdles to the overall bilateral relations,” he wrote.
China’s positioning last year of an oil drill rig in disputed waters off the Vietnamese coast seems finally to have triggered the old guard in the Communist Party to consider playing the America card.
It has much to gain. An easing of US defence sales could enhance Hanoi’s capabilities in disputed waters and there’s an opportunity to invigorate momentum for TPP, the Trans-Pacific Partnership, that Vietnam hopes will boost export led growth.
The Washington meetings perhaps hold even more resonance for domestic politics in Vietnam, riven as they with factional infighting in the run up to next year’s party Congress and change of leadership.
Human rights activists hope for more US pressure on the party to stop the jailing and harassment of bloggers and other government critics.
They express concern, however, that Washington could lose interest in their plight as it woos Vietnam as a buffer against China’s ambitions in South-East Asia.
There’s also unease about the enhanced recognition for the Communist Party’s role implied by the entertainment of its top official in the White House.
Still, democracy campaigners in Vietnam see opportunities.
“If the party follows China too closely, it will lose Vietnamese territory and waters and sacrifice our sovereignty,” says a researcher in Ho Chi Minh City, who does not want to be named for fear of reprisals.
“But if it gets too close to the United States it risks losing power,” he says.
The party is fully aware of the potentially explosive consequences of making mistakes in the intricate diplomatic dance needed to play Washington off against Beijing.
“A few years ago the party would not allow any open discussion of relations with China, but they had to give way. If they kept silent now there would be an uprising,” said the researcher.
Anti-China demonstrations culminating in riots and the destruction of foreign owned factories have spawned a new more vibrant political climate.
Many of the new generation of civil society activists were inspired by the demonstrations that took place outside the Chinese embassy and consulate in Hanoi and HCMC.
The party knows its legitimacy is at stake if it is seen as too cosy with its ideological comrades in Beijing.
But it will also be cautious to keep the US from too intimate an embrace.
A recent research by the Pew Research Centre indicated that 76% of Vietnamese held a favourable view of the United States, one of the highest in the world, with younger Vietnamese being the most positive of all.
It’s a detail not lost to Vietnamese activists that Mr Trong has been a particularly low profile party boss who has allowed much of the political initiative to pass to the prime minister’s office.
He is also due to step within six months or so of his meeting with President Obama.
Playing in the United States in this way may be seen as a trump card by the ideologues in Hanoi, but it raises the stakes in a multidimensional game that is as much about who governs Vietnam and how, as it is about international diplomacy and the strategic balance in the South China Sea.