Moon Jae-in, President of South Korea said on Friday lack of progress in de-nuclearization talks between North Korea and the United States was the most regrettable thing for him last year, along with a slower-than-expected improvement in the living conditions of South Koreans.

He especially mentioned the no-deal Hanoi summit between U.S. President Donald Trump and the North's leader Kim Jong-un during a phone interview with an SBS radio program.

"If there had been some headway in the North Korea-U.S. dialogue, (we) could have advanced peace on the Korean Peninsula and South-North cooperation," he said.

He also cited separated families living on the other side of the border of the two Koreas, as he was speaking on the occasion of the Lunar New Year, called Seol in Korean. It's one of the biggest annual celebrations for Koreans.