Nikki Haley

The US, Britain and France were among the countries that skipped a UN meeting to discuss a new treaty.

More than 120 others endorsed a plan for a legally binding nuclear ban.

But US envoy Nikki Haley said national security required nuclear arms because of "bad actors" who could not be trusted.

"There is nothing I want more for my family than a world with no nuclear weapons. But we have to be realistic," she told reporters.

"Is there anyone that believes that North Korea would agree to a ban on nuclear weapons?"

The former Republican governor of South Carolina vowed there is a "new US UN."

Haley told reporters, "Our goal with the administration is to show value at the UN, and the way to show value is to show our strength, show our full voice. Have the backs of our allies and make sure our allies have our backs as well."

She then added, "For those who don't have our backs, we're taking names, and we will make points to respond to that accordingly."

South Carolina Governor Nikki Haley was nominated as US envoy to the UN and Betsy DeVos as education secretary.

Both are former critics of Mr Trump, with Mrs Haley once saying she was "not a fan", and Mrs DeVos branding the Manhattan tycoon an "interloper".

Mr Trump's presidential primary rival Ben Carson also hinted he would soon be named for a post.

"An announcement is forthcoming about my role in helping to make America great again," Mr Carson wrote on Facebook.

The Republican's about-face comes after nine black church members were gunned down, allegedly by a young white man who embraced the flag as a symbol of white supremacy.

"150 years after the end of the Civil War, the time has come," Haley said after rousing applause, surrounded by Democrats and Republican lawmakers. "That flag, while an integral part of the past, does not represent the future of our great state"

The flag has flown in front of the state capitol for 15 years after being moved from atop the Statehouse dome.