The official said it's a "matter of course" to seek such a declaration because denuclearization is one of the three key agenda items for the April 27 summit, along with bringing permanent peace on the Korean Peninsula and improving inter-Korean relations.

In another development, Japan’s Foreign Minister Taro Kono is arranging his first visit to South Korea next week, ahead of the inter-Korean summit. He plans to meet President Moon Jae-in and request that he bring up the issue of the North’s abductions of Japanese nationals in the 1970s and 1980s in his meeting with North Korean leader Kim Jong Un. Kono also plans talks with his counterpart, Kang Kyung-wha, and seek her cooperation in improving bilateral ties, which have been strained over the comfort women issue.