Britain's Prince Harry told the UN that the overturning of constitutional rights in the United States was part of "a global assault on democracy and freedom."
The Duke of Sussex addressed the United Nations General Assembly in New York at an event marking Nelson Mandela International Day.
"This has been a painful year in a painful decade," the royal told delegates.
He cited the continuing fallout from the pandemic, climate change, disinformation, and Russia's invasion of Ukraine before alluding to the Supreme Court's recent overturning of America's nationwide right to abortion.
"And from the horrific war in Ukraine to the rolling back of constitutional rights here in the United States, we are witnessing a global assault on democracy and freedom, the cause of Mandela's life," Harry said.
The royal paid tribute to Mandela, South Africa's anti-apartheid hero who spent 27 years in prison before being elected the country's first Black leader, as "not only a man of conscience" but "a man of action."
Harry, 37, invoked that sentiment to urge leaders to tackle climate change, as his wife Meghan Markle looked on from the chamber.
"As we sit here today, our world is on fire again," said the prince, adding that "historic weather events are no longer historic."
"More and more, they are part of our daily lives. And this crisis will only grow worse unless our leaders lead."
"Unless the countries represented by the seats in this hallowed hall make the decisions, the daring, transformative decisions that our world needs to save humanity," he added.
The General Assembly designated July 18, Mandela's birthday, Nelson Mandela Day in 2009 to honor his life and legacy.
Assembly president Abdulla Shahid and New York City Mayor Eric Adams were among other delegates to make speeches.
In a personal moment, Harry said a photograph of his mother Princess Diana with Mandela is "on my wall and in my heart every day."
It was taken in Cape Town in 1997, a few months before Diana's death in a car crash in Paris.
"When I first looked at the photo, straightaway what jumped out was the joy on my mother's face. The playfulness, cheekiness even, the pure delight to be in communion with another soul so committed to serving humanity," said Harry. (AFP)