The United States under Donald Trump’s presidency will not allow other countries to increase their nuclear capability without responding in kind, a spokesman for the president-elect said yesterday.
“There are countries around the globe right now that are talking about increasing their nuclear capacity,” Sean Spicer, the incoming White House press secretary, told CNN.
“And the United States is not going to sit back and allow that to happen without acting in kind,” he said, when pressed to explain a Trump tweet calling for the US to “greatly strengthen and expand its nuclear capability.”
“I think the president-elect is very clear that he’s going to be very active in putting America’s security first and foremost,” Spicer said.
“And if another country wants to threaten our sovereignty or our safety he will act.”
Asked if he was referring specifically to Moscow, Spicer replied: “It’s not just about one country. It’s any country.”
Shortly earlier, Trump was quoted as having told an MSNBC host – when asked to clarify his nuclear policy tweet – that his administration had no reservations about entering “an arms race.” 
The network’s Mika Brzezinksi said she spoke to the president-elect during a commercial break, after concluding an on-air interview with Spicer.
“This morning he told me on the phone, ‘Let it be an arms race. We’ll outmatch them at every pass and outlast them all,’” Brzezinski said.
Shares of uranium producers and a nuclear fuel technology company have jumped on Trump’s comments with Uranium Resources Inc, Uranium Energy Corp, Cameco Corp and Lightbridge Corp all trading higher yesterday.
It was not clear what prompted Thursday’s tweet by Trump, a Republican who takes office on January 20.
Observers have been scrambling since Thursday to make sense of Trump’s assertion that the US must massively bolster its nuclear capabilities, which he tweeted without providing details or context, a day after meeting a group of Pentagon top brass, and shortly after President Vladimir Putin called for Russia to reinforce its own nuclear capabilities.
“The United States must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes,” Trump tweeted.
America currently has an estimated arsenal of about 7,000 nuclear warheads, second only to Russia, which has a few hundred more.
The Pentagon wants to replace or modernise all three legs of its “triad,” a three-pronged nuclear attack force comprising intercontinental ballistic missiles (ICBMs), submarines and bombers.
Experts estimate the cost will hit $1tn over the next 30 years.
Laicie Heeley, a nuclear expert at the Stimson Centre, a nonpartisan anti-nuclear proliferation think tank in Washington, said it was “reckless” for Trump to tweet on the topic without offering details.
“To make such a loaded statement without context or follow-up is irresponsible at best,” she said.
“We could be talking about a return to the Cold War here, when the threat of a nuclear catastrophe was very real. Russian rhetoric is already moving in that direction. It wouldn’t take a lot to bring us back there.”
During the presidential campaign debates, Trump was unable to provide specifics when asked what his priority would be for the nuclear triad, saying: “For me, nuclear, the power, the devastation is very important to me.”