Speaking in Canada on Saturday, Air Force General John Hyten said he had given a lot of thought to what he would say if he was to be given an "illegal" order to launch nuclear weapons by President Donald Trump. Hyten is responsible for overseeing the US nuclear arsenal. 

Addressing his audience at the Halifax International Security Forum in Nova Scotia, Hyten said: "I think some people think we're stupid," in response to a question about such a scenario. "We're not stupid people. We think about these things a lot. When you have this responsibility, how do you not think about it?"

In the event that Trump decided to launch a nuclear attack, Hyten said he would only provide the President with strike options that were legal.

"If it's illegal, guess what's going to happen. I'm going to say, 'Mr. President, that's illegal.' And guess what he's going to do? He's going to say, 'What would be legal?'" Hyten said.

"And we'll come up with options with a mix of capabilities to respond to whatever the situation is, and that's the way it works."

Donald Trump's history-to-date of unpredictable and volatile behavior in his role as US President has raised concerns that he could unilaterally order a nuclear attack – an issue that was also recently debated by members of the US Senate.

'Illegal' vs 'imminent'

In the event of an ongoing or imminent nuclear attack, senators and expert witnesses agreed that the president had full authority to defend the nation, but experts said there was no strict definition of "imminent."

As to what constitutes an "illegal" order, Hyten referred to the four key principles from the Law of Armed Conflict in his remarks.

"The Law of Armed Conflict has certain principles – necessity, distinction, proportionality, unnecessary suffering – all those things are defined," said Hyten.

"If you execute an unlawful order, you will go to jail, you could go to jail for the rest of your life. It applies to nuclear weapons, it applies to small arms, it applies to small unit tactics, it applies to everything."

During testimony before the Foreign Relations Committee earlier this month, retired General Robert Kehler who served as the head of Strategic Command from January 2011 to November 2013, also said that the US armed forces were obligated to follow legal orders, not illegal ones.

Conflict with North Korea

The comments came as the threat of nuclear attack from North Korea remained a serious concern. Trump's taunting tweets aimed at Pyongyang have sparked concerns primarily among congressional Democrats that he may be inciting a war with North Korea.

Trump threatened to unleash "fire and fury" on North Korea and began calling Kim Jong-Un "Rocket Man" after a series of missile tests in the North, while the hermit state's leader branded Trump as "deranged" and referred to him as a "dotard."

Read more: White House again rejects talks with North Korea

ss/jm (AP, AFP)