Donald Trump’s plans to mitigate and deal with a national crisis have been described as a "black box" as key staff leave their posts and crucial vacancies remain unfilled.

As Mr Trump heads to Washington DC to be sworn in as 45th President of the US, his state department of defence remains largely unfilled below cabinet level.

The staffing gap became even more apparent after Fox News commentator Monica Crowley withdrew from her appointment as deputy national security adviser for strategic communications amid accusations she had plagiarized passages of her 2012 book and her doctoral dissertation.

The day before Mr Trump is handed the nuclear codes, the National Security Council’s strategy, and who will staff it, remains a guessing game.

The hiring and firing of the NSC - up to 200 staff need to be appointed - is being overseen by incoming national security adviser and retired general Michael Flynn, who has no NSC experience. He has also regularly tweeted out fake news and conspiracy theories, and described Islam as a "cancer". In a bid to be fully briefed, he has met four times with Mr Obama’s counterpart, Susan Rice, who told the New York Times they were "racing to make up lost time".

The available roles include senior directors who handle issues like the Middle East, Russia, Afghanistan, economic sanctions and nuclear proliferation, as reported by Politico.

Donald Trump's controversial cabinet

His deputy, Fox News anchor KT McFarland, has slightly more experience as she was a typist and research assistant at the NSC when Richard Nixon and Gerald Ford were in office.

"This isn't getting attention it deserves. Who will run and implement policy? Right now there is a big vacuum," Max Boot, a military historian and fellow at the Council on Foreign Relations, said on Twitter.

Lt. Gen. Michael Flynn (Ret) says islam is a political ideology and not a religion

The President-elect has appointed far short of the 4,000 overall government positions he has to make.

The Trump team is reportedly trying to avoid appointing foreign policy experts who were against his Presidency, in line with the incoming administration’s policy to blacklist Never Trumpers.

Mr Trump appointed retired general Keith Kellogg to be the NSC chief of staff, and speculation abounds about a couple of other appointees, many of which have military experience, but lack government experience or the knowledge on how to deal with a domestic crisis.

Almost two dozen Trump appointees joined an Obama staffer-led emergency meeting last weekend to discuss how to deal with natural disasters, but in the case of a terrorist attack, Mr Trump’s government might have to meet such a crisis with an understaffed team.