North Korea's leader Kim Jong Un and U.S. President Donald Trump talk in the garden of the Metropole hotel during the second North Korea-U.S. summit in Hanoi, Vietnam February 28, 2019. REUTERS/Leah Millis

HANOI (Reuters) - South Korea said it regretted that no deal was reached at a summit between North Korean leader Kim Jong Un and U.S. President Donald Trump on Thursday but the two sides had made meaningful progress.

Trump said he had walked away from a nuclear deal at his second meeting with Kim, in Vietnam, because Kim had made unacceptable demands on lifting biting U.S.-led sanctions.

South Korea’s presidential office, known as the Blue House, said in a statement Trump and Kim made “more meaningful progress than ever”, and Trump’s willingness to continue dialogue would brighten prospects for another meeting.