FILE PHOTO: North Korean leader Kim Jong Un and U.S. President Donald Trump listen to questions from the media during their one-on-one bilateral meeting at the second North Korea-U.S. summit in the Metropole hotel in Hanoi, Vietnam February 28, 2019. REUTERS/Leah Millis/File Photo

WASHINGTON (Reuters) - U.S. President Donald Trump said on Twitter on Friday that his talks with North Korean leader Kim Jong Un in Hanoi had been “substantive,” adding, “We know what they want and they know what we must have.”

The second summit between Trump and Kim collapsed in Vietnam on Thursday without any agreement or immediate plan for a third meeting between the two leaders or their delegations.

The two sides gave different reasons for the abrupt end in talks about denuclearization on the Korean Peninsula. Trump told reporters on Thursday that North Korea wanted all of the sanctions lifted in their entirety.

But the North Korean foreign minister Ri Yong Ho disputed that claim during a midnight news conference, saying North Korea had asked only for a partial lifting of the sanctions in exchange for dismantling its main nuclear site at Yongbyon.

South Korean President Moon Jae-in, who has actively supported the talks, said South Korea will work with the United States and North Korea to ensure an agreement on denuclearization.