Donald Trump came to Helsinki to clear his name of collusion. Instead the US president soiled it and with it, dragged the world further down a path towards previously unthinkable instability.
It has been 70 years since the future of the western democratic alliance was so precariously poised between chaos and certainty. Standing next to Russian President Vladimir Putin, following their secretive two-hour meeting, it seemed both men wanted nothing more than to deny they ever knew each other before Mr Trump's election.
Yet in a rare fumble, Mr Putin admitted he wanted Mr Trump to win the tarnished 2016 US election that his intelligence agents are indicted with interfering in. "Yes I did," he told a stunned audience.
This perhaps was not so much a concession; rather, it was from over-exuberance born not out of his KGB training, which teaches always to remain in control of emotions, but of a job well done – undermining his biggest global adversary and setting in motion fractures that will further cleave America from its traditional allies.
As Mr Putin left Helsinki, his foreign minister captured the Russian mood, calling the day "magnificent" and "better than super".
Only days earlier, Mr Trump had sat in Winston Churchill's chair in the house where the great British wartime leader was born. He struck a pose that suggested he was reliving those moments when Churchill's resolve was all that stood between chaos and calamity.
It feels appropriate to paraphrase Britain's best-loved leader to understand Mr Trump's utter failure to deliver on US national security interests and that of its allies in Helsinki: never before in the field of presidential summits has one leader given so much for so little, at the cost of so many.
Mr Trump's capitulation to Mr Putin's lies on live television, watched by millions across the world, is sending diplomatic shockwaves way beyond Washington.
In the hours following the summit, the silence from Mr Trump's European allies was deafening. Had he stood up to Mr Putin and warned him not to attack the US by interfering in its elections again, there might well have been more applause from Berlin and London.
Russia stands accused of interfering in elections in these countries too. A message for one, a message for all.
Leaving Washington earlier this month, Mr Trump said his meeting with Mr Putin would be the easiest of his trip to Europe – easier than his meetings at Nato or in the UK. No one could have imagined that his seven days in Europe – ripping through his allies, lambasting German chancellor Angela Merkel and undermining British Prime Minister Theresa May – would end with him being given a football by Mr Putin that he'll pass on to his son.
Not only has Mr Trump betrayed US intelligence services by putting himself ahead of his country but he is also betraying his allies. If he doesn't believe his own intelligence services, the logic follows, how can he be trusted to believe his allies' intelligence services and what those leaders tell him? How can they harness their national strategic security interests to the US if its president doesn't look out for his own and they have no idea where he is going? This is not the America they signed up to partner with.
Mr Trump's recent confrontations over trade tariffs, his offhand comments this weekend that the European Union "is a foe" of the US, now coupled with the collapse of his diplomatic integrity at Mr Putin's feet, will look to many like the start of a new world order. As bi-partisan opprobrium rains down on Mr Trump in the US, his European allies are beginning to crystallise their thinking.
At Nato's headquarters, Mr Trump indicated he was more inclined to side with Mr Putin over his illegal 2014 annexation of Crimea than his allies. When asked last Thursday if he would recognise Crimea as part of Russia he responded: "That’s an interesting question, because long before I got here President Obama let that happen."
His allies had heard that line before. But what came next was the shocker: the idea that because Mr Putin had spent money in Crimea, it might somehow give him legitimacy. "They just opened a big bridge that was started years ago. They built, I think, a submarine port adding billions of dollars," Trump told the crowded room.
A minute later he was asked: "Will you consider stopping military exercises in the Baltic states?"
When Mr Trump met North Korean dictator Kim Jong-un in Singapore last month, he surprised his South Korean allies by unilaterally giving Mr Kim the concession of stopping joint military exercises. The equivalent for Nato would be backing down on joint military exercises in the Baltic states.
Latvia, Lithuania and Estonia are on the frontline with Russia and fear their own Crimea moment may be around the corner. Nato has a tripwire force in each of the Baltic states: about 1,000 or so troops to send a figurative flare should there be a Russian incursion, as happened in Ukraine. At which point, tens of thousands more Nato forces currently on 48-hour standby in Europe would be rushed in. It is significant, but insufficient to contain a serious Russian assault.
Mr Trump hinted that this deployment and the bigger Nato military exercises they support could be cut down. "Well, perhaps we'll talk about that," he said in answer to the question. A response guaranteed to send shockwaves through the already jittery Baltic states, who only escaped the brutal ugliness of Soviet repression a quarter-century ago. The following day, when standing next to British Prime Minister Theresa May, Mr Trump was again asked about the US military commitment to Europe.
His response: "There is a psychological and a military benefit. There is also a benefit not to do it." It was hardly the ringing endorsement America's European allies would hope for and more reason for worry as he headed to Helsinki.
If US troop deployments, military exercises or Crimea came up during Mr Putin and Mr Trump's meeting, neither of them mentioned it during their subsequent press conference. Absent an independent read-out of what was actually discussed in that room, Mr Trump's allies cannot feel reassured that their interests are being considered. Since Mr Trump's election in 2016, many of his European allies have shown increasing concern over his destabilising impact on the world.
At the EU's first emergency summit to discuss concerns about Mr Trump – held days after his inauguration – both the German chancellor and the then French president agreed that Europe could no longer rely on US leadership.
European rumblings of dissatisfaction have only grown since then. On climate, trade and now security, dangerous chasms are opening up after 70 years of relative calm. During those decades, America has been a stabilising force for good over historic European divisions.
If the Helsinki summit does become a crystallising moment and Mr Trump's follies force old allies apart, it could also be judged as the moment a new, more unstable world order was created.
That's not the achievement for which this great city of Helsinki, revered for advancing human rights and stabilising global relations, was previously known.
Nic Robertson is CNN's international diplomatic editor