Donald Trump: 'Let it be a nuclear arms race'

• Report by ITV News Washington Correspondent Robert Moore

Donald Trump has declared that the United States would "outmatch" and "outlast" other countries in expanding its nuclear arsenal - declaring: "Let it be an arms race".

It comes after the President-elect tweeted on Thursday, saying the US "must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes."

In a telephone conversation with MSNBC's Mika Brzezinski on Friday, he was asked to expand on what he meant.

She said he responded: "Let it be an arms race. We will outmatch them at every pass and outlast them all."

Separately, his newly-appointed official spokesman Sean Spicer insisted there would not be an arms race because Mr Trump would ensure that other countries trying to expand their nuclear capabilities - such as Russia and China - would think again.

Speaking to NBC, he said:

It was not immediately clear what prompted Mr Trump's initial tweet, though it came just hours after Russian President Vladimir Putin gave a speech in which he said his country needed to boost its nuclear weaponry to ensure it could "neutralise" threats.

Shares in several uranium producers and a nuclear fuel technology company jumped on Trump's comments, with Uranium Resources Inc, Uranium Energy Corp, Cameco Corp and Lightbridge Corp all trading higher on Friday.