South Korean President Moon Jae-in said Tuesday it was too early to be pessimistic about stalled denuclearization dialogue between the United States and North Korea, and that inter-Korean cooperation could help ease the way for sanctions to be lifted.

Despite hostile rhetoric from Pyongyang, North Korea has not conducted a weapons test nor shut the door to more talks even after Washington ignored its year-end deadline to make concessions, Moon told an annual New Year news conference.

"North Korea made clear that the door to dialogue is not closed though there's a premise that they can come back to talks only when their demands are accepted," he said.