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.