Western leaders have rallied round Joe Biden at the Nato summit, amid concerns about the US president's age and ability to serve another term.
Calls are growing for Mr Biden to drop out of the presidential race this November, and his attempts to diminish fears about his re-election bid at the summit were marred by two serious gaffes.
French President Emmanuel Macron said Mr Biden was "in charge" and "clear on the issues he knows well", while UK PM Sir Keir Starmer said he was "on good form".
But Mr Biden's first gaffe, in which he introduced Ukrainian leader Volodymyr Zelensky as President Putin, was ridiculed in the Russian media.
And later in a news conference - Mr Biden's first unscripted public appearance since the debate - he referred to his "Vice-President Trump" when meaning to say Kamala Harris.
The US president has been under pressure to quit since a disastrous performance two weeks ago in a debate with his Republican rival in the upcoming elections, Donald Trump.
But throughout the summit, other Nato leaders have defended him and his ability to lead.
Mr Macron, speaking after Thursday's White House dinner, said he had had a long discussion with Mr Biden during the meal, and appealed for understanding of his flaws.
"I saw him as always a president who is in charge, clear on the issues he knows well," he said.
"We all make slips of the tongue sometimes. It has happened to me before, it will probably happen to me tomorrow.
"I would ask you to show the same leniency that should be shown between caring people."
German Chancellor Olaf Scholz also addressed the gaffes.
“Slips of the tongue happen, and if you always monitor everyone, you will find enough of them," he said.
UK Prime Minister Sir Keir said repeatedly during the summit that the US president had achieved much to be proud of there, and was "across all the detail".
On Friday he added: "We've been through two days of this council and come to a very good outcome... And I think he should be given credit for that."
Canadian Prime Minister Justin Trudeau said it was a privilege and a pleasure to work with Mr Biden.
"[Biden's] depth of experience, his thoughtfulness, his steadfastness on the greatest issues and challenges of our time is a credit to the work that we're all doing together," he said.
Polish President Andrzej Duda, seen as being close to former President Trump, said, quoted by AFP: "I talked with President Biden, and there is no doubt that everything is ok."
Meanwhile Finnish President Alexander Stubb combined a defence of Mr Biden with fears about the atmosphere in the US elections.
"I have absolutely no concern about the capacity of the current president of the United States to lead his country and to lead our fight for Ukraine and to lead Nato," he said, quoted by AFP.
"The only thing I'm worried about is that the political climate in the United States right now is too toxic, is very polarised, and that doesn't leave enough room for a civilised and constructive debate."
Not all Nato leaders were prepared to weigh in on behalf of Mr Biden, though.
Hungarian Prime Minister Viktor Orbán reportedly made almost no comments to the media in Washington.
Instead he left immediately after the end of the summit for Mar-a-Lago, Mr Trump's Florida residence, where the two men talked about the war in Ukraine.
"We discussed ways to make peace," Mr Orbán said on social media. "The good news of the day: he's going to solve it!"
But if leaders of allied countries have been unwilling to criticise the US president for his frailties, Moscow has been similarly restrained.
Kremlin spokesman Dmitry Peskov said the gaffes were clearly slips of the tongue and "not our business, an internal matter for the USA".
Not so the Russian media, which have been all over Mr Biden's confusion of Mr Putin with Mr Zelensky.
Official Rossiya TV showed it at the top of its 9pm bulletin, saying that "America's vassals pretended that they'd not noticed anything".
NTV said Biden had never been so close to a fiasco and that his "latest slip of the tongue is worthy of an Oscar".
And popular daily Moskovsky Komsomolets ran an article headlined "Senile Leaders", comparing Joe Biden to the elderly Communist leaders of the USSR.
"What's more dangerous, a monkey with a grenade or a shaking hand on the nuclear button?" it asked.
Additional reporting by Vitaliy Shevchenko
