US President Donald Trump has confirmed that the United States plans to leave a landmark nuclear weapons treaty with Russia over claims Moscow has violated the deal.

"Russia has not adhered to the agreement. So we are going to terminate the agreement," Mr Trump told reporters in Elko, Nevada.

He added: "Russia has violated the agreement. They've been violating it for many years.

"I don't know why president Obama didn't negotiate or pull out. And we're not going to let them violate a nuclear agreement and go out and do weapons we're not allowed to."