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President Donald Trump vowed to "de-nuke" the world on Thursday while continuing to insist that he has vastly upgraded America's nuclear arsenal in just seven months in office.

"I would like to de-nuke the world," Trump said. “Until such time as they do, we will be the most powerful nuclear nation in the world, by far."

When questioned on how he could have made that arsenal more powerful without the decades that a large-scale modernization would take, the president insisted he'd done a lot already and would continue to do so.

"We’ve done a lot of modernization, we’ve done a lot of renovation, it will be in a lot better shape in the next six months or a year," he said, repeating the claim he made on Twitter a day earlier.

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But experts and Democratic lawmakers said there’s no evidence that Trump has upgraded the nation’s nuclear arsenal.

Former Secretary of Energy Ernest Muniz, who managed the nation's nuclear arsenal until Trump was inaugurated, disputed Trump's claim.

"The arsenal, of course, is the same one we had on January 20," he told MSNBC's Andrea Mitchell.

My first order as President was to renovate and modernize our nuclear arsenal. It is now far stronger and more powerful than ever before.... — Donald J. Trump (@realDonaldTrump) August 9, 2017

...Hopefully we will never have to use this power, but there will never be a time that we are not the most powerful nation in the world! — Donald J. Trump (@realDonaldTrump) August 9, 2017

What’s more, because of how Congress works, any changes the president could have made to the nuclear arsenal could not take effect before next year anyway. In fact, the arsenal Trump is boasting about is the one maintained by President Barack Obama.

Trump ordered a rebuilding of the American military and assessing its readiness on January 27th, a week into office. In that order, Trump called for a "Nuclear Posture Review," an analysis designed to help the new administration understand its existing arsenal and how it meets strategic needs.

Neither have any direct effect on the nuclear arsenal that the nation has today.

"Under the Constitution, Congress controls nuclear modernization as part of its power to organize, equip, and fund of our armed forces. President Trump’s requests related to nuclear weapons modernization have not yet passed Congress, and nothing he has done would even begin to take effect until 2018," said Rep. Adam Smith, ranking member of the House Armed Services Committee, in an email.

"The only thing he has done so far is sign a presidential memorandum requiring a nuclear posture review, but the review is nowhere near complete," he added.

Col. Jack Jacobs, an NBC News military analyst and Medal of Honor recipient, likened the president's order to Obama's efforts to close the prison Guantanamo Bay, which were ultimately unsuccessful.

"In order to make something happen, Congress has to approve it and approve an authorization bill that authorizes the expenditure of the money and, separately, an appropriations bill that directs the government to write the check for it," he said. "Neither one of those things have occurred."

Obama undertook gradual upgrades to the nuclear arsenal and he supported a $1 trillion process for modernization last year. Trump has requested a huge uptick in nuclear spending — a 11 percent increase over the current year’s appropriation. But for now those plans are simply that.