President Joe Biden has formally apologised for the US's role in running abusive Native American boarding schools for more than 150 years and was heckled at the event by a Gaza war protester.
"This to me is one of the most consequential things I've ever had an opportunity to do in my whole career," Mr Biden said in his apology in Arizona.
"It's a sin on our soul. … I formally apologise."
Hundreds of people attended the event and many of them were wearing traditional tribal clothing.
The crowd cheered as the US president apologised to the Native American community for the generational trauma caused by the boarding schools.
Heckled by Gaza protester
Hundreds of people were at the event and many were wearing traditional clothing. (AP Photo: Manuel Balce Ceneta)
Mr Biden faced a brief interruption when a pro-Palestinian protester shouted "how can you apologise for a genocide while committing a genocide in Palestine?"
The president replied, "there is a lot of innocent people being killed and it has to stop."
Washington's support for Israel's wars in Gaza and Lebanon, after the October 7 Hamas attack on Israel last year, has led to months of demonstrations across the US.
Tens of thousands of civilians have been killed in the region and Palestinians in Gaza have grappled with hunger and disease.
Rights advocates have demanded an arms embargo against Israel.
Israel and Washington deny genocide allegations brought against Israel in relation to Gaza at the World Court and Washington has maintained its support for its ally Israel.
Friday's trip marked Mr Biden's first time visiting Indian Country while in office and is part of his effort to cement his legacy in his final months in the White House.
Arizona is also one of the seven battleground states in a tight race for the November 5 US election in which Democratic Vice-President Kamala Harris faces Republican former president Donald Trump.
Troubled legacy
Secretary Haaland launched an investigation into federal Native American boarding school policies. (AP Photo: Manuel Balce Ceneta)
The first Native American to be a cabinet secretary, US Interior Secretary Deb Haaland, launched an investigation to recognise the troubled legacy of federal Native American boarding school policies.
An Interior Department investigative report released in July found that at least 973 children died in these schools.
Secretary Haaland's family members were among the children forced into the boarding schools.
From 1819 to the 1970s, the US implemented policies establishing and supporting hundreds of American Indian boarding schools across the country.
The purpose was to culturally assimilate Native Americans by forcibly removing them from their families, communities, religions and cultural beliefs.
In recent years, Australia, New Zealand and Canada have also reviewed past abuse toward Indigenous communities, including children in schools.
Mr Biden's move mirrors Kevin Rudd's 2008 apology, which saw the then-prime minister formally say sorry to thousands of stolen First Nations children.