echelon command all the way down to the missile silo to carry out an order. >> reporter: but the president decided to challenge kim jong-un on who has the biggest button. "i, too, have a nuclear button, but it is a much bigger and more powerful one than his, and my button works." trump was responding to kim's statement -- >> translator: the entire continent of america is within reach of our nuclear attack. they must never forget, the nuclear button's placed on my desk at all times. >> reporter: like all presidents, mr. trump has been briefed and detailed from the beginning on nuclear launch procedures. a military officer is nearby at all times with everything the president needs. former white house military official bill gully wrote in" book "breaking cover" that the football, or presidential emergency satchel, historically contains a list of strike options, authentication codes, a list of secure bunkers where the