President-elect Donald Trump said Thursday that America must massively boost its nuclear capability until the "world comes to its senses."

"The United States must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes," Trump wrote on Twitter, without explaining what he meant.

His comment marks a jarring departure from President Barack Obama's rhetoric, who in a famous speech in Prague in 2009 called for the elimination of nuclear weapons.

Trump's tweet came the day after he met with a group of Pentagon brass including Vice Admiral James Syring, who heads the Missile Defense Agency.

The conversations centered on cutting costs to various military programs.

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 modernize 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 $1 trillion over the next 30 years.

During the presidential campaign debates, Trump was unable to provide specifics when asked what his priority would be for the nuclear triad, saying "the power, the devastation is very important."

"I think we need somebody absolutely that we can trust, who is totally responsible, who really knows what he or she is doing. That is so powerful and so important," he said at the time.

"The biggest problem we have today is nuclear, nuclear proliferation and having some maniac, having some madman go out and get a nuclear weapon. That's in my opinion, that is the single biggest problem that our country faces right now."