World leaders have condemned the violent scenes in Washington, where rioters supporting US President Donald Trump stormed the Capitol building.
The action forced the suspension of a joint session of Congress to certify Joe Biden's electoral victory.
Many leaders called for peace and an orderly transition of power, describing what happened as "horrifying" and an "attack on democracy".
UK Prime Minister Boris Johnson condemned the "disgraceful scenes".
"The United States stands for democracy around the world and it is now vital that there should be a peaceful and orderly transfer of power," he wrote on Twitter.
Other UK politicians joined him in criticising the violence, with opposition leader Sir Keir Starmer calling it a "direct attack on democracy".
Scotland's First Minister Nicola Sturgeon tweeted that the scenes from the Capitol were "utterly horrifying".
The scenes from the Capitol are utterly horrifying. Solidarity with those in 🇺🇸 on the side of democracy and the peaceful and constitutional transfer of power. Shame on those who have incited this attack on democracy.
— Nicola Sturgeon (@NicolaSturgeon) January 6, 2021
Spanish Prime Minister Pedro Sánchez said: "I have trust in the strength of US democracy. The new presidency of Joe Biden will overcome this tense stage, uniting the American people."
French Foreign Minister Jean-Yves Le Drian condemned the "grave attack against democracy", while his German counterpart, Heiko Maas, said Mr Trump and his supporters "must accept the decision of American voters at last and stop trampling on democracy".
European Council President Charles Michel said he trusted the US "to ensure a peaceful transfer of power" to Mr Biden, and European Commission President Ursula von der Leyen said she looked forward to working with the Democrat.
— Charles Michel (@eucopresident) January 6, 2021
Nato Secretary-General Jens Stoltenberg joined those in saying that the outcome of the election "must be respected".
Canada's Prime Minister Justin Trudeau said Canadians were "deeply disturbed and saddened by the attack on democracy".
"Violence will never succeed in overruling the will of the people. Democracy in the US must be upheld - and it will be," he wrote on Twitter.
From New Zealand, Prime Minister Jacinda Ardern, tweeted that "democracy - the right of people to exercise a vote, have their voice heard and then have that decision upheld peacefully - should never be undone by a mob".
Australian Prime Minister Scott Morrison condemned the "distressing scenes" and said he looked forward to a peaceful transfer of power.
India's Narendra Modi said he was "distressed to see news about rioting and violence" in Washington and urged the "peaceful transfer of power must continue".
Distressed to see news about rioting and violence in Washington DC. Orderly and peaceful transfer of power must continue. The democratic process cannot be allowed to be subverted through unlawful protests.
— Narendra Modi (@narendramodi) January 7, 2021
The Turkish foreign ministry said it invited "all parties" to show "restraint and common sense".
The Venezuelan government said that "with this regrettable episode, the United States suffers the same thing that it has generated in other countries with its policies of aggression".
In statements on Twitter, Argentina's President Alberto Fernández and Chile's President Sebastián Piñera also condemned the scenes in Washington.
Mr Piñera said Chile "trusts in the solidity of US democracy to guarantee the rule of law".
In India, Prime Minister Narendra Modi, who is known to have previously forged a good relationship with Mr Trump, said he was "distressed to see news about rioting and violence".
"Orderly and peaceful transfer of power must continue. The democratic process cannot be allowed to be subverted through unlawful protests," he tweeted.
In Japan, Chief Cabinet Secretary Katsunobu Kato said it hoped for a "peaceful transfer of power" in the United States.
From Fiji, Prime Minister Frank Bainimarama, who led a coup in 2006, also expressed outrage at the events that took place.
The violent scenes we saw in Washington today are an affront to democracies around the globe. True and genuine democracy is a precious treasure that no nation should ever take for granted. We are confident the USA will soon close this ugly chapter once and for all.
— Frank Bainimarama (@FijiPM) January 7, 2021
And in Singapore, the country's Senior Minister Teo Chee Hean said he had watched as the "shocking" scenes took place, adding: "Its a sad day".