(Bloomberg) -- President-elect Donald Trump said Thursday the U.S. should enlarge its nuclear arsenal, an apparent reversal of a decades-long reduction of the nation's atomic weaponry that came hours after Russian President Vladimir Putin said his country's arsenal should also be strengthened.

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

Putin said in a speech earlier on Thursday that his country should also bolster its nuclear forces: "We need to enhance the combat capability of strategic nuclear forces, primarily by strengthening missile complexes that will be guaranteed to penetrate existing and future missile defense systems," he said.

The Global X Uranium ETF rose to a session high after Trump's comments while Uranium Resources, a Colorado-based mining company, climbed as much as 27% before trimming gains.

President Barack Obama has both reduced the U.S. nuclear arsenal, in an agreement early in his presidency with Russia, and sought to modernize it to replace thousands of bombs and missiles. His modernization plan — which the Arms Control Association said would cost as much as $1 trillion over 30 years — has come under criticism from proponents of denuclearization, who warn it may prompt a new arms race with Russia and China.

More broadly, Trump has said he will seek to enlarge the U.S. military, including by building dozens of new ships for the Navy, while controlling costs.

'BOW WAVE'

Lockheed Martin, Boeing and Northrop Grumman are already competing to build a next generation of intercontinental ballistic missiles for the Air Force, a project expected to cost at least $85 billion. That is just one part of a modernization plan which will contribute to what defense analysts call a gathering "bow wave" of spending in the coming decade on major weapons that future presidents will face.

Defense companies stand to benefit from a resurgence in military spending promised by Trump and already underway in Western Europe and Asia as global tensions rise. Trump met Wednesday with executives from both Lockheed Martin and Boeing in Florida, along with a bevy of top Pentagon officials, to discuss military spending. Among the participants was Vice Admiral James Syring, who heads the Pentagon's Missile Defense Agency.

"We're trying to get costs down, costs," Trump told reporters in brief remarks outside the resort after the officers departed.

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