President Donald Trump said his summit with North Korean dictator Kim Jong Un collapsed Thursday after Kim demanded total relief from economic sanctions in exchange for closing only some nuclear sites.

“This wasn’t a walkaway like you get up and walk out. No, this was very friendly. We shook hands.”

Kim “wanted the sanctions lifted in their entirety and we couldn’t do that,” Trump said at a news conference in Hanoi, Vietnam. “They were willing to give us areas but not the ones we wanted.”

Trump says Kim offered to shutter North Korea’s most important nuclear facility if the U.S. would relinquish on the major economic sanctions imposed, but wouldn’t do the same for other areas of its nuclear weapons program.

“Sometimes you have to walk,” Trump said of the negotiations.

“It was about the sanctions,” he added. “Basically they wanted the sanctions lifted in their entirety, but we couldn’t do that.”

So the two sides remain deadlocked, with North Korea keeping its nuclear arsenal and facilities, and the U.S.’s crippling economic sanctions remaining in place.

Per the New York Times:

Word of the collapse of the Hanoi talks sent stocks lower in Asia, and Wall Street futures were down as the opening bell neared.

Mr. Trump had flown across the world to try to work face-to-face with Mr. Kim for the second time, an effort to reduce what American officials regard as one of the world’s foremost nuclear threats. Experts estimate that the North has 30 to 60 nuclear warheads as well as intercontinental ballistic missiles that can hit the United States, though it has not demonstrated the technology to protect warheads as they re-enter the atmosphere.

Before ending the news conference to fly back to Washington, Mr. Trump tried to put a good face on the outcome. “This wasn’t a walkaway like you get up and walk out,” he said. “No, this was very friendly. We shook hands.”

“There’s a warmth that we have and I hope that stays,” he added.

Mr. Trump said that Mr. Kim had pledged to maintain a halt on nuclear and ballistic missile tests that is now in its 16th month, and that the negotiations would continue.

The sticking point turned on what it would take for North Korea to begin dismantling a central part of its nuclear program, an enrichment facility, Yongbyon, which Kim said he would do only with full sanctions relief.

But Mr. Trump and Mr. Pompeo said the North would have to dismantle other parts of its program as well before the United States agreed to such a big concession.

In response to a question, Mr. Trump acknowledged for the first time that his administration was aware of a second enrichment site other than Yongbyon, but it was unclear what role that played in the talks.

The United States has long insisted that sanctions will be lifted only after North Korea completely dismantles its nuclear program in a verifiable manner. There was talk before the summit meeting, though, that Mr. Trump might agree to ease sanctions in exchange for initial steps toward denuclearization by allowing joint economic projects between North and South Korea.

It was not immediately clear if Mr. Trump made such an offer or how Mr. Kim responded.