U.S. President Donald Trump is leaving Hanoi earlier than his planned departure at 6:05 p.m.

He and North Korea Chairman Kim Jong-un entered the second day of their summit in Hanoi on Thursday but eventually failed to reach an agreement on denuclearization.

Trump told reporters at a press conference later that it was North Korea's desire to see the back of sanctions that had derailed talks.

"Basically they wanted the sanctions lifted in their entirety, and we couldn't do that," he said.

"We haven't given up anything," Trump said.

"He wants to denuke, he just wants to do areas that are less important than what we want," Trump said of Kim.

"We want to give up the sanctions because that country has so much economic potentials. But only when they agree to give up their nuclear," Trump said.

He said his relationship with Kim remains good, but there's currently no plan for the third summit.