It's a plain, bulging leather satchel, but inside it has the ominous power to unleash a nuclear armageddon.

And tomorrow it falls into Donald Trump's control.

When he is sworn in as president, Mr Trump inherits control of the "football," the briefcase that carries the procedures and communications equipment that allow the US leader to launch nuclear missiles.

The bag, aluminum-framed and weighing 20kg goes everywhere he goes, carried by a military aid.

Mr Trump also gets, with the satchel, the "biscuit" - a pocket-sized card with the codes the president needs to authenticate his command to launch a nuclear attack.

The football has been omnipresent with the leader of the world's most powerful nation since around 1963, according to Smithsonian magazine.

It has to stay close to the president, given that he will have less than five minutes to react before nuclear missiles launched at the US by an airstrike.

It is the president's sole decision, and he must input the codes in secure communications with a Pentagon command and control centre to launch US nuclear weapons.

"He doesn't have to check with anybody," vice president Dick Cheney said in 2008.

"He doesn't have to call the Congress. He doesn't have to check with the courts. He has that authority because of the nature of the world we live in."

Given that the power accrues to him as soon as he is sworn in as president today, Mr Trump will have been briefed on the procedures of the football, which contains documents outlining his choices for an attack: how strong it should be and which targets to hit, for example.

A former White House military aide, Col. Buzz Patterson, compared the documents to a fast-food restaurant menu.

"It's like picking one out of Column A and two out of Column B," he said, according to Smithsonian.

Responsibility for US nuclear power was made an issue in the presidential election. President Barack Obama sassed Mr Trump during the election campaign last year as too "erratic" to be entrusted with that power.

"If somebody can't handle a Twitter account, they can't handle the nuclear codes," Mr Obama quipped.

Mr Trump is indeed a newcomer to the issues of deterrence strategy, but in December he made clear his view that the US must maintain a powerful nuclear arsenal.

Responding to Russian President Vladimir Putin's statement that Moscow needs to strengthen its own nuclear force, Mr Trump responded by tweet: "The United States must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes."