The first summit between US President Joe Biden and his Russian counterpart was "constructive," Vladimir Putin said after the three-and-a-half-hour meeting in Geneva.

"The talks were absolutely constructive," Putin said during a solo press conference in Geneva, where both leaders agreed to the return of their respective ambassadors, a gesture of appeasement in their tense relations.

The ambassadors "will return to their workplace. When exactly is a purely technical question," said the Russian president, who also advanced possible "commitments" for a prisoner exchange.

Diplomatic relations between Moscow and Washington have been very degraded since the current US president came to power in January.

After Biden compared Putin to a "murderer," Russia called its ambassador Anatoli Antonov for consultations in March and said his American counterpart in Moscow, John Sullivan, should return to Washington.

Despite the tensions, the summit held in the elegant Villa La Grange began with a handshake between the two leaders.

Biden took the initiative and held out his hand to Putin. "It is always better to meet face to face," the American said at the beginning of the first meeting with the Russian leader since he arrived at the White House.

Putin arrived in Geneva on Wednesday at noon, half an hour before the start of the meeting, and Biden did so on Tuesday, from Brussels, where he participated in both NATO summits and with his allies in the European Union.

Since coming to power, the 46th president of the United States has adopted a firm tone regarding Putin, to make clear the differences with his untimely predecessor, Donald Trump. Biden also promised that he will highlight to his counterpart which are "the red lines" that he should not cross.

"I am not seeking a conflict with Russia, but we will respond if Russia continues its harmful activities," the US president said before the summit.

Although the White House insisted that no spectacular progress should be expected, the 78-year-old president knows that in Geneva he has the opportunity to polish his image as an excellent negotiator.

In recent days, observers recalled the famous summit in Geneva between Presidents Ronald Reagan and Mikhail Gorbachev in 1985, which marked the beginning of the thaw of the Cold War.

"I am always ready," declared Biden when he arrived in Geneva and was questioned about his state of mind before this meeting that concentrates the attention of the world.

But the Russian president also has long experience with summits. Since coming to power in late 1999, he has already rubbed shoulders with four US presidents. Biden is the fifth.

Many experts agree that Putin has already achieved what he most wanted: holding the summit as a sign of Russia's importance on the world stage.

In an interview with NBC, Putin said he expected the Democratic president to be less impulsive than his Republican predecessor. But he took advantage of the occasion to describe Donald Trump as a "talented" man.

The only point of agreement between the White House and the Kremlin was that relations between the two countries are at their lowest point in decades.

The subjects of controversy are numerous and the discussions promised to be acrimonious and difficult, in particular on Ukraine and Belarus.

One of the most sensitive topics is online misinformation and cyber attacks.

Putin said in this regard that he agreed with Biden "to open a dialogue on cybersecurity."

Beyond the attempted interference in the 2016 elections, recent massive cyberattacks against companies such as SolarWinds, Colonial Pipeline and JBS and attributed to Moscow or Russian-based hacking groups, have upset Washington.

The city is under tight security, but a small group of protesters wanted to show their support for Aléxei Navalni, a Russian opposition leader who is in prison after surviving a poisoning that he attributes to the Kremlin. Many chanted "A Russia without Putin."

On Tuesday, from Brussels, Joe Biden issued a clear warning about the Russian activist. Navalni's death "would be a tragedy," Biden said. "That would deteriorate relations with the rest of the world and also with me," he warned.

Navalni "knew he was breaking the law" by not respecting the conditions of a suspended sentence when he was treated in Germany for poisoning, the Russian president said after the summit on Wednesday.

The President of Switzerland, Guy Parmelin, for his part, was hopeful about this meeting.

"The world has been 18 months into a pandemic that hit terribly. The Geneva meeting represents an opportunity for the presidents of the United States and Russia to instill a little more optimism, a little more hope in world politics," he said.