North Korea has rejected the main reason U.S. President Donald Trump gave for cutting short his summit with leader Kim Jong Un, with Foreign Minister Ri Yong Ho saying Friday at a rare press conference that Pyongyang did not urge Washington to lift sanctions entirely but only partially.

"What we have asked for was partial lifting of sanctions, not in their entirety. In detail, we asked to lift five sanctions that were imposed within 2016 and 2017 out of a total of 11 U.N. sanctions and which affect ordinary people's livelihoods," Ri said at the midnight press conference in Hanoi.

North Korean Vice Foreign Minister Choe Son Hui said at the same press conference that Kim seems to have "lost motivation" to negotiate with the United States.

Choe reiterated her doubts over Kim's willingness to continue talks with Trump during an interview later Friday with South Korean news outlets in the Vietnamese capital.

"I (got) a feeling that (Kim) is changing his thought a bit" toward negotiations with the United States, Choe said.

The state-run Korean Central News Agency reported early Friday morning that Trump and Kim will continue "productive" talks, without mentioning the failure to reach an agreement.

The North Korean officials' remarks came after Trump and Kim cut short their summit on Thursday without an agreement, with Trump telling a press conference that the two leaders had failed to bridge the gap between U.S. insistence on full-fledged denuclearization measures and Pyongyang's demand for full sanctions relief.

The rare appearance by the North Korean officials at a press conference appears to be an effort by Pyongyang to blame Washington for the failure to create a written agreement at the meeting.

Ri also said North Korea told the United States that Pyongyang would "eternally" dismantle the country's main Yongbyon nuclear complex if the sanctions were partially lifted, while proposing to Washington a written pledge that it would end nuclear and ballistic missile tests.

Trump said at his press conference that the lifting of the sanctions would require North Korea to scrap other nuclear facilities and programs, including undeclared ones.

Later Friday, a senior U.S. State Department official who is engaged in talks with North Korea slightly modified Trump's remarks, saying Pyongyang called for Washington to lift all the sanctions "except for weapons."

As for the Yongbyon nuclear complex, the official told reporters that North Korea vowed to close down "a portion of" it, even though it is a sprawling complex with many buildings and institutions.

The facility is an "important entity to define because the Yongbyon complex since the early 1990s has been at the center of the North Korean nuclear weapons program," the official added.

At an inter-Korean summit in September last year in Pyongyang, Kim promised to permanently disassemble the Yongbyon nuclear complex, around 100 kilometers north of the North's capital, if the United States were to take reciprocal steps.

Kim has recently committed to building a "powerful socialist economy" instead of bolstering his armed forces. But international sanctions aimed at preventing Pyongyang from pursuing nuclear and ballistic missile programs have weighed on North Korea's economic development, foreign affairs experts say.

Neither Ri nor Choe, however, said Friday that North Korea would abandon its nuclear weapons, suggesting Pyongyang has no intention of discarding its existing nuclear arsenal.

KCNA reported that Trump and Kim "met again" on Thursday following the first day of the two-day summit and that the leaders "had a constructive and candid exchange of their opinions over the practical issues arising in opening up a new era" of the improvement of U.S.-North Korea relations.

"They agreed to keep in close touch with each other for the denuclearization of the Korean peninsula and the epochal development of the DPRK-U.S. relations in the future, too, and continue productive dialogues for settling the issues discussed at the Hanoi Summit," the news agency said.

DPRK is the acronym of North Korea's official name, the Democratic People's Republic of Korea.

The White House also said Trump told Japanese Prime Minister Shinzo Abe and South Korea President Moon Jae In during separate telephone conversations that he will continue talks with Kim.

Trump left Hanoi by air on Thursday afternoon, while Kim is scheduled to stay in the Vietnamese capital through Saturday.

Despite the failure to produce an accord in the Hanoi summit, Trump struck a positive note about the meeting's results and the prospect for future negotiations with Pyongyang in a tweet Friday, saying he "had very substantive negotiations with Kim Jong Un."

"We know what they want and they know what we must have. Relationship very good, let's see what happens!" he posted.

At their historic first meeting in Singapore in June 2018, Trump and Kim made an agreement that Washington would provide security guarantees to Pyongyang in return for "complete denuclearization" of the Korean Peninsula.

But U.S.-North Korea negotiations have shown little sign of moving forward, due largely to the Trump administration's skepticism over Pyongyang's seriousness about giving up nuclear weapons.