Russian President Vladimir Putin said Wednesday that Moscow and Washington agreed for their ambassadors to return, after talks in Geneva with US counterpart Joe Biden.

"They will return to their place of work. When exactly is a purely technical question," Putin told reporters after a summit in Geneva.

Diplomatic relations between Moscow and Washington had all but broken down since Biden took office.

After Biden likened Putin to a "killer", Russia in March took the rare step of recalling its ambassador Anatoly Antonov and said the US envoy John Sullivan to Moscow likewise should return to Washington. 

Sullivan left Moscow in April, as the two countries announced a wave of tit-for-tat sanctions and expulsions of diplomats. 

In May, Russia formally designated the United States an "unfriendly" state, barring its embassy from employing Russian nationals. The only other country on that list is the Czech Republic.

Putin says US-Russia summit 'constructive'

A first summit between US President Joe Biden and his Russian counterpart was "constructive", Vladimir Putin said Wednesday after the talks in Geneva ended.

"The conversation was absolutely constructive", Putin told reporters, adding that the sides had agreed for their ambassadors to return in a small gesture of healing in their strained relations.

The ambassadors "will return to their place of work. When exactly is a purely technical question," Putin told reporters after the summit, which lasted about three and a half hours.

Diplomatic relations between Moscow and Washington had all but broken down since Biden took office in January.

After Biden likened Putin to a "killer", Russia in March took the rare step of recalling its ambassador Anatoly Antonov. The US envoy, John Sullivan, likewise returned to Washington.

Despite tensions, the summit at an elegant villa on the shore of Lake Geneva got off to a good start, with the two leaders shaking hands and striking cautiously positive notes. 

Biden, who was set to hold a separate press conference later, pressed Putin to replace the combustible US-Russian stand-off with a more "predictable" relationship between "two great powers" capable of agreeing to disagree.

He stressed his desire to take US-Russian relations off their increasingly unstable trajectory, in which Washington accuses the Kremlin of everything from meddling in elections to cyberwarfare.

"It's always better to meet face to face," he told Putin as they met in the villa's library, with a globe placed between them.

"We are trying to determine where we have a mutual interest, where we can cooperate; and where we don't, establish a predictable and rational way in which we disagree -- two great powers," Biden said.

Putin noted at the start of the meeting that "a lot of issues" need addressing "at the highest level" and that he hoped the meeting would be "productive".

At his press conference after the summit, Putin signalled progress in a number of areas, including an agreement to "start consultations on cybersecurity".

But Putin also rejected Biden's frequent criticism over his human record and allegations of harbouring cyber criminals, saying that in fact "the largest number of cyberattacks in the world are carried out from the US space."

Cold War, new problems 

Biden's apparent offer of a more understanding -- if not necessarily a friendly relationship -- went a long way toward what Putin is reportedly seeking: increased respect on the world stage.

The reference to the United States and Russia as "two great powers" was sure to please the Kremlin leader, who has dominated his country for two decades, infuriating the West with invasions of Ukraine and Georgia, and often brutal crushing of political dissent.

Expectations were low for anything more than a modest thaw in relations.

Illustrating the frostiness, there was no shared meal during the talks, which were attended by the two countries' foreign ministers and later by an expanded group of officials.

The choice of Geneva recalled the Cold War summit between US president Ronald Reagan and Soviet leader Mikhail Gorbachev in the Swiss city in 1985.

The summit villa, encircled with barbed wire, was under intense security. Grey patrol boats cruised along the lake front and heavily-armed camouflaged troops stood guard at a nearby yacht marina.

But in contrast with 1985, tensions are less about strategic nuclear weapons and competing ideologies than what the Biden administration sees as an increasingly rogue regime.

From cyberattacks on American entities and meddling in the last two US presidential elections, to human rights violations and aggression against Ukraine and other European countries, Washington's list of allegations against the Kremlin runs long.

Putin came to the summit arguing that Moscow is simply challenging US hegemony -- part of a bid to promote a so-called "multi-polar" world that has seen Russia draw close with the US's arguably even more powerful adversary China.

In a pre-summit interview with NBC News, he scoffed at allegations that he had anything to do with cyberattacks or the near-fatal poisoning of one of his last remaining domestic opponents, Alexei Navalny.

Worthy adversary

Biden, ending an intensive first foreign trip as president, arrived in Geneva after summits with NATO and the European Union in Brussels, and a G7 summit in Britain.

While in Brussels, he said he would detail his "red lines."

"I'm not looking for conflict," he said, but "we will respond if Russia continues its harmful activities".

However, Biden, who had previously characterised Putin as a "killer", upgraded the Russian leader to "worthy adversary".

And for all the rhetoric, the White House and Kremlin both say they are open to doing business in a limited way.

Officials point to the recent extension of the New START nuclear arms limitation treaty as an example of successful diplomacy.

Unlike in 2018, when Biden's predecessor Donald Trump met Putin in Helsinki, there was to be no joint press conference at the end of the summit.

The US side clearly wanted to avoid the optics of having Biden sharing that kind of platform with the Russian president.

In 2018, Trump caused a stir by saying, as Putin stood beside him, that he believed the Kremlin leader over his own intelligence services when it came to accusations of Russian interference in the 2016 US presidential election bringing Trump to power.