Secretary of State Mike Pompeo said Sunday that North Korea remains a nuclear threat, contradicting a tweet last year by President Trump.

Pompeo made the remark in an interview on CNN’s “State of the Union” days before Trump holds his second summit with North Korean leader Kim Jong Un.

Asked by CNN’s Jake Tapper whether he believes North Korea remains a nuclear threat, Pompeo responded, “Yes.”

After last year’s summit with Kim in Singapore, Trump tweeted, “There is no longer a Nuclear Threat from North Korea. Meeting with Kim Jong Un was an interesting and very positive experience.”

But Pompeo on Sunday disputed that Trump had said as much.

“What he said was that the efforts that had been made in Singapore — this commitment that Chairman Kim made — have substantially taken down the risks to the American people. It’s the mission of the secretary of state and the president of the United States to keep the American people secure. We’re aiming to achieve that,” the secretary of state said.

Pompeo also said that Trump is focused on ensuring that Kim takes “demonstrable” steps toward denuclearization as a result of this week’s summit in Hanoi.

He maintained that there has been “no change” in the U.S. position on sanctions relief, while also indicating that the North Koreans could receive some relief for taking verifiable steps toward denuclearization. The past U.S. position had been that any sanctions relief would be contingent on full denuclearization.

Wide gaps remain between U.S. and North Korean negotiators, who have yet to agree on a basic definition of what “denuclearization” means to both sides, U.S. officials told The Washington Post.

Trump’s approach to North Korea has drawn criticism from Democrats, who warn that holding “photo ops” with Kim risks legitimizing him as a leader and undermining U.S. national security goals.

Eight Senate Democrats, including Minority Leader Charles E. Schumer (N.Y.), sent a letter to Trump on Sunday urging him to produce a “serious diplomatic plan” and calling for regular classified briefings on the North Korean nuclear issue.

“We believe your next meeting with Kim thus must demonstrate tangible, verifiable progress on denuclearization and reducing tensions with the North,” the senators said in the letter.

Trump has maintained that his strategy of engaging Kim has paid off. On Sunday morning, the president tweeted that he and Kim “expect a continuation of the progress made at first Summit in Singapore.”

“Denuclearization?” he added, providing no specifics.

In a follow-up tweet, Trump said that Chinese President Xi Jinping had been “very helpful in his support” of the summit and that “the last thing China wants are large scale nuclear weapons right next door.”

China, however, has long been North Korea’s closest ally, and, from a strategic perspective, the status quo presents Beijing with stability — and geopolitical leverage — that a denuclearized North Korea could imperil.

Others on Sunday were less than optimistic about the second Trump-Kim summit’s chances of success.

Former New Mexico governor Bill Richardson, who has at times served as an unofficial envoy to North Korea, said on ABC’s “This Week” that the prospects for real progress were dim.

“I think the president deserves credit for lowering tensions in the region,” Richardson said. “But in terms of concrete accomplishments, I don’t think this summit’s going to produce [any].”

David Nakamura contributed to this report.