Washington (CNN)President Donald Trump warned North Korean leader Kim Jong Un on Tuesday that he has a nuclear "button" on his desk at all times and boasted that the US has "much bigger & more powerful" nuclear weapons -- a stunning threat that has once again raised questions over what it takes to actually launch a nuclear warhead.

"The system is not a button that the President can accidentally lean on against the desk and immediately cause missiles to fly as some people in the public, I think, fear it would be," Feaver testified.

He added that the decision to launch a strike requires the President to work with military aides possessing the materials he needs to order an attack, as well as personnel at all levels, from top commanders all the way down to service members working in the missile silos.

Whether he is at the White House, in a motorcade, aboard Air Force One or on a trip overseas, Trump is never more than an arm's reach away as the aide carrying the football rides in the same elevator, stays on the same hotel floor and is protected by the same Secret Service agents.