The North called South Korean officials through the liaison office established at the truce village of Panmunjom at 9.03AM (local time), the official said on condition of anonymity. He said the move appears to be a follow-up on the North's announcement to return to the unified time zone effective last Saturday, adding that the two Koreas will see an end to the abnormal situations caused by the difference in standard times.

Meanwhile, South Korean President Moon Jae-in vowed to help Japan improve its ties with North Korea, calling it key to denuclearizing the North and enhancing peace and stability across the Korean peninsula.

Moon said in an interview with Japan's Yomiuri Shimbun published on Tuesday that Japan can play a very important role for peace and prosperity on the Korean Peninsula. The normalization of North Korea-Japan relations may be a necessary factor for a security guarantee for the North. He also said the close cooperation between South Korea, the US and Japan may be necessary for complete denuclearization of the Korean Peninsula.

The normalization of relations will also contribute greatly to peace and stability of the Northeast Asian region as a whole, President Moon said.

Japan’s Foreign Minister Taro Kono said he expects the upcoming summit between Japan, China, and South Korea to focus on ending the North’s missile and nuclear program.