Donald Trump outlined his belief that a pre-emptive strike against North Korea may be necessary in an interview in 1999.

Eighteen years before he became US president Mr Trump talked at length with CNN about the prospect of the rogue nation becoming a nuclear power.

He also described what he would do if he was president.

Mr Trump told CNN: "If spoken to correctly - correctly - they will play ball.

"You start negotiating. If you don't stop them you will have to take rather drastic action because if you don't take them now, you're going to be in awfully big trouble in five years when they have more missiles than we do."

He added: "We're a bunch of saps."

Mr Trump was asked whether "rather drastic action" would mean something like Israel's unilateral strike on Iraq's Osirak reactor in 1981.

He said: "You can never rule it out. What Israel did was fantastic. That's what they (North Korea) are afraid of.

"Don't react in five years because if you react in five years nothing's going to be left, you won't have to worry about your social security system."