President Trump acknowledged his changed tone on North Korea during remarks at a UN luncheon on Wednesday.

"Last year my tone was somewhat different on North Korea than it is now," Trump said.

He said he was expecting progress in his dealings with Kim Jong Un, but acknowledged: "As the expression goes, who knows."

During his address to the UN last year, Trump called Kim "Rocket Man" and warned warned the US would "totally destroy North Korea" if forced to defend itself or its allies

But this year, he said North Korea has taken "encouraging measures" following his summer summit with Kim. He even thanked the North Korean leader for the country's progress.