One mystery has been solved as Donald Trump implied that his "calm before storm" remark was indeed about North Korea. "We can't let this go on" with Pyongyang, he said when asked to clarify his phrase which sparked speculation in the media.

In a Fox News interview with Sean Hannity on Wednesday, the first question that Trump was asked was whether he was thinking of North Korea when he made his enigmatic comment earlier in October. "It seems related to 'Rocket Man' Kim Jong-un… in terms of them [North Korea] having nuclear capability," Hannity said.

Trump essentially confirmed that he was making the remark about Kim. However, he didn't specify the message.

"We can't let this go on. We just can't," Trump said, responding to Hannity's question.

Trump made the mysterious comment last week following his meeting with senior US military officials at the White House. When reporters arrived, the president said: "This is the calm before the storm."

"What's the storm? On Iran? On ISIS? On what?" one of the reporters asked.

"We have the world's great military people," Trump replied. "Thank you all for coming."

When asked by an NBC News reporter one more time what "storm" he had referred to, Trump said "You'll find out."