North Korean leader Kim Jong Un has vowed to shut down the country’s nuclear test site in May and open the process to experts and journalists from South Korea and the United States, Seoul’s presidential office said Sunday.

Kim made the comments during his summit with South Korean President Moon Jae-in on Friday at a border truce village, where he also expressed optimism about his anticipated meeting with Donald Trump, saying the U.S. president will learn he’s “not a person” to fire missiles toward the United States, Moon’s spokesman Yoon Young-chan said.

Moon and Kim during the summit promised to work toward the “complete denuclearization” of the Korean Peninsula, but made no references to verification or timetables. Seoul had also shuttled between Pyongyang and Washington to set up a potential meeting between Kim and Trump, which is expected next month or early June.

“Once we start talking, the United States will know that I am not a person to launch nuclear weapons at South Korea, the Pacific or the United States,” Yoon quoted Kim as saying.

“If we maintain frequent meetings and build trust with the United States and receive promises for an end to the war and a non-aggression treaty, then why would be need to live in difficulty by keeping our nuclear weapons?” Yoon quoted Kim as saying.

North Korea this month announced it has suspended all tests of nuclear devices and intercontinental ballistic missiles and plans to close its nuclear testing ground.

Kim reacted to skepticism that the North would only be closing down the northernmost test tunnel at the site in Punggye-ri, which some analysts say became too unstable to conduct further underground detonations following the country’s sixth and most powerful nuclear test in September. In his conversation with Moon, Kim denied that he would be merely clearing out damaged goods, saying that the site also has two new tunnels that are larger than previous testing facilities, Yoon said.

Yoon said Kim also revealed plans to re-adjust its current time zone to match the South’s.

The Koreas used the same time zone for decades before the North in 2015 created its own “Pyongyang Time” by setting the clock 30 minutes behind South Korea and Japan.

North Korean then explained the decision as an effort to remove a legacy of Japanese colonial rule. Local time in South Korea and Japan is the same — nine hours ahead of Greenwich Mean Time. It was set during Japan’s rule over the Korean Peninsula from 1910 to 1945.

Yoon said that the North’s decision to return to the Seoul time zone was aimed at facilitating communication with South Korea and also the United States.