"This is yet one more step in ensuring that we're prepared", General David Goldfein, the US Air Force chief of staff, told reporters during a tour of American bases.
As the escalatory rhetoric continues and the situation reaches touch-and-go, Trump told Fox News, "we are so prepared like you wouldn't believe.you would be shocked to see how totally prepared we are, if we need to be".
An editorial by North Korean government news agency KCNA said: "Dignitaries of White House, and State and Defense Departments of the USA are having a hard time cooling Trump overheated with a war fever, but only the south Korean puppet forces are fanning up the lunatic fingering a nuclear button". It's never been more important to make sure that we get this mission right'.
Goldfein and other senior defense officials stressed that despite the alert having not yet been given, it could come. The final decision lies in the hands of Gen. John Hyten, head of US Strategic Command, which is responsible for the US army's nuclear forces, or Gen. Lori Robinson, head of US Northern Command, which is responsible for defending North America, Defense One said.
Goldfein said that the order to return the B-52 bombers to high-readiness has not yet been issued, but showed journalists the ongoing construction work at Barksdale Air Force Base in Louisiana.
Goldfein said: "The world is a risky place and we've got folks that are talking openly about use of nuclear weapons". The base is also being refurbished to allow the bombers to "take off at a moment's notice".
Specifically, he said, General Goldfein told airmen to think beyond Cold War uses for ICBMs, bombers and nuclear cruise missiles.
Additionally, Goldfein said that Barksdale and other U.S. bases are building storage facilities for new intercontinental ballistic missiles.
The development is the latest in the nuclear stand-off developing between the United States and North Korea that has witnessed Pyongyang growing its nuclear arsenal and developing its weapons program.
Mr Goldfein's comments came after the director of the Central Intelligence Agency said North Korea was months away from perfecting its nuclear weapons. "We provide best military advice and options for the commander in chief and the secretary of defense".
The U.S.is considering putting some nuclear bombers on 24-hour alert.
One painting - a symbol of the Cold War - depicts a silhouette of a B-52 with the words "Peace The Old Fashioned Way", written underneath.