Daily SumUp

In the same interview, Mr Trump also threatened Iran with secondary tariffs and potential military action if the country didn't come to an agreement with Washington over its nuclear program.

Mr Trump said US and Iranian officials were talking but did not elaborate.

"If they don't make a deal, there will be bombing," Mr Trump told NBC News.

"But there's a chance that if they don't make a deal, that I will do secondary tariffs on them like I did four years ago."

In his first term, Mr Trump withdrew the US from a 2015 deal between Iran and world powers that placed strict limits on Tehran's disputed nuclear activities in exchange for sanctions relief.

Mr Trump also reimposed sweeping US sanctions. 

Since then the Islamic Republic has far surpassed the agreed limits in its escalating program of uranium enrichment.

Tehran has so far rebuffed Trump's warning to make a deal or face military consequences.