President Trump said early Thursday he failed to reach a deal with North Korea's leader Kim Jong-un because of a disagreement over sanctions, as talks abruptly wrapped up on the second day of their summit in Hanoi, Vietnam.

Why it matters: Trump said Kim pledged to dismantle the Yongbyon nuclear facility — not its entire nuclear program — if all sanctions imposed on the country were lifted first. "Sometimes you have to walk,” he said. Kim had a vision of denuclearization, that's "not exactly our vision, but it's a lot closer than it was a year ago."

Trump and Kim canceled a planned lunch after their morning talks and left in separate cars. Kim did not commit to holding another summit, Trump said, but he insisted the two leaders had a "good relationship."

Kim said of the denuclearization goal: “If I’m not willing to do that, I won’t be here right now.” Trump said the two leaders could have signed a deal Thursday. “But it’s better to do it right than do it fast,” he said.

Trump added: "Basically, they wanted the sanctions lifted in their entirety, and we couldn't do that."

Other big takeaways: Trump stressed earlier there was no rush to reach an agreement. "We just want to do the right deal,” he said.