US President-elect Donald Trump has called for the country to expand its nuclear weapons capabilities until the world “comes to its senses” – a signal he may support costly efforts to modernise the ageing US nuclear arsenal.

During the next decade, US ballistic missile submarines, bombers, and land-based missiles – the three legs of the nuclear triad – are expected to reach the end of their useful lives.

Maintaining and modernising the arsenal is expected to cost at about $1 trillion over 30 years, according to independent estimates.

“The United States must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes,” Mr Trump said in a post on Twitter.

The United States must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes

— Donald J. Trump (@realDonaldTrump) December 22, 2016

Mr Trump, who is at his Florida resort for the Christmas holiday, gave no details about what prompted his tweet.

A spokesman later said Mr Trump’s statement referred to the need to prevent nuclear weapons from spreading to unstable countries or terrorist groups.

“President-elect Trump was referring to the threat of nuclear proliferation and the critical need to prevent it – particularly to and among terrorist organisations and unstable and rogue regimes,” spokesman Jason Miller said.

Mr Trump, who won the US election on November 8 and takes office on January 20, campaigned on a platform of building up the US military, but also pledged to cut taxes and control federal spending.

Mr Trump met on Wednesday (local time) with a dozen Pentagon officials involved with defence acquisition programs, as well as the chief executives of Lockheed Martin Corp and Boeing Co, the country’s two largest defence contractors.

Mr Trump said he talked with the chief executives about lowering costs for two high-profile programs: Lockheed Martin’s F-35 fighter jets and Boeing’s replacement 747-8s for the presidential Air Force One plane.

Mr Putin and Mr Trump’s relationship was mocked on the final episode of SNL for 2016.

Defence stocks were little changed after Mr Trump’s tweet, but shares of small uranium miners including Uranium Resources Inc and Uranium Energy Corp rose sharply.

Putin also calls to strengthen nuclear capability

Russian President Vladimir Putin told an annual end-of-year meeting with defence chiefs that Russia’s military could overpower any potential foe but should strengthen its nuclear arsenal.

“We can say with certainty: we are stronger now than any potential aggressor,” he told the meeting. “Anyone!”

His comments come at the end of a year when tensions between Russia and the West have remained on edge over the civil war in Syria.