Michael McFaul, a former US ambassador in Moscow, branded the Russian leader a Brexit "winner" after the final votes had been counted.
He wrote: "Shocked by Brexit vote! Losers: EU, UK, US, those that believe in utility of a strong, united, democratic Europe. Winners: Putin.
"I genuinely complement Putin for his victory tonight on Brexit. Tonight is giant victory for Putin's foreign policy objectives."
The Kremlin appeared to back up speculation that Moscow was celebrating the 'Out' vote, with a spokesman saying officials were hoping for a thaw in relations with London.
Kremlin spokesman Dmitry Peskov said: "We have a pretty heavy burden of uneasy ties with Great Britain. "We hope that in the new realities, an understanding of the need for good relations with our country will prevail."
John Oliver is an excellent cultural ambassador to the US - so thank god he's been on hand to explain to people across the pond what is going on in the EU referendum.
On the latest episode of This Week Tonight Oliver has to first off explain for clueless Americans what the vote is, that it could have major implications for the world economy, and what the EU is, even.
A whole host of changes will be on the way when Britain leaves the European Union after the referendum on Thursday (June 23). Harlow voted strongly, by 68 per cent, in favour of withdrawing from the EU. However what happens next is still an unknown.
Whatever way you voted, here are seven things that will change when Britain does leave the block. The price of shopping for everyday goods is expected to rise in the short term as Britain currently relies on imports from Europe.
Travel plans should continue as normal, however immigration rights will change. Expect to see a new design for the passport soon. The price of going on holiday could also rise with the value of the pound currently weaker against the Euro.
Free movement of people in the European Union will come to an end. It is yet to be decided as to what this will mean for EU citizens living in the UK who have been here for less than five years and not able to claim residency.
The most vocal architect of Britain's seismic decision to leave the European Union thumbed his nose at the EU Parliament Tuesday as members booed and turned their backs on him, in the most visible clash of ideologies between Britain and Europe since last week's vote.
Nigel Farage, leader of the far-right UK Independence Party (UKIP), gloated unapologetically and antagonized a battered union in Brussels, calling for free trade with the bloc while insulting members in the same breath.
"Isn't it funny? When I came here 17 years ago and I said that I wanted to lead a campaign to get Britain out of the European Union, you all laughed at me. Well, I have to say, you're not laughing now, are you?" he said.
Leave's 17.4 million voters did not have to give a reason when they cast their votes last week, but many of them will have done so as a way to tackle immigration.
Remainers are pushing the idea that voters have been misled by Leavers, citing Daniel Hannan's claim that any Leave voters expecting big changes on the immigration front would be “disappointed”.
The Tory MEP has suggested that Britain will keep access to the single market once it has left the European Union, thus still allowing the free movement of labour from Europe. So how fair is it to accuse Brexiteers of selling Britain a pup over immigration?
The Vote Leave campaign didn't say so overtly, preferring to talk of a Leave vote helping Britain "take control" of the rate of immigration rather than how far they could cut it by. Their campaigners cast a vote to Remain as a vote for "uncontrolled immigration", making hay with the Prime Minister's struggle to fulfill his net migration pledge and implying that Leave would rein it in. Boris Johnson did as such back in March, warning that Mr Cameron's failure to get it under control was "deeply corrosive of public trust".