Changes to the nation’s nuclear arsenal take years, to say nothing of hundreds of billions of dollars to implement. When President Obama last conducted a Nuclear Posture Review in 2010, he outlined steps to modernize the “nuclear triad” of submarines, bombers, and intercontinental ballistic missiles. (Trump infamously had no idea what the triad was during a 2015 GOP primary debate.) That process is not meant to be completed until the 2020s.

Trump has made statements that suggest he’s taking a rather different approach to nuclear weapons than his predecessor. Obama sought to control nuclear proliferation worldwide, announced limitations on when the U.S. would use nuclear weapons, and signed a treaty with Russia in 2010 called New START, which capped nuclear deployment for the two countries.

During the campaign, Trump suggested that nuclear proliferation by American allies in Asia might be a good thing, breaking with decades of American orthodoxy on proliferation. In December, he tweeted that he wanted the U.S. to expand its nuclear capability and arsenal, startling arms experts, world leaders, and apparently some of his own aides, who worked to walk it back. During a January call with Russian President Vladimir Putin, Trump had to stop to ask aides what the New START treaty was, but then said he didn’t like the deal. But this saber-rattling, while not inconsequential, has not been connected to material changes. Meanwhile, a planned reduction in ICBMs has moved forward. Is Trump lying, or does he actually believe he has already revolutionized the U.S. nuclear posture? Neither option is pleasant to contemplate.

One reason Trump’s untruth on Wednesday is so peculiar is that regardless of the policy specifics, experts assess that the U.S. nuclear arsenal has long been, continues to be, and will remain large enough to render the world uninhabitable several times over. Trump’s messaging often suggests an obsession with toughness and machismo, but there are limitations to aggressiveness. The problem that the U.S. faces in North Korea is not that its nuclear deterrent is insufficient; it’s that the American nuclear threat hasn’t convinced North Korea to stop building its own nuclear weapons. Pyongyang has concluded that successive U.S. administrations are unwilling to take the risk of either a conventional or nuclear war to stop the North Korean nuclear program.

It may be too late for anyone to change that impression among North Korean leaders. But it’s not the size of the American arsenal that will change their mind—it will require them being convinced that the U.S. poses a credible threat. Few things undermine the credibility of the U.S. president like Trump’s easily debunked lies.