South Korean President Moon Jae-in asked that the United Nations help verify North Korea’s planned shutdown of its Punggye-ri nuclear test site in a phone conversation on Tuesday with U.N. Secretary-General Antonio Guterres, South Korea’s presidential Blue House said.

Guterres said the requests need approval from the U.N. Security Council, but he wanted to cooperate to build peace on the Korean peninsula and would assign a U.N. official in charge of arms control to cooperate with South Korea, the Blue House spokesman Kim Eui-kyeom added.

Several days before the inter-Korean summit on Friday (April 27), the North surprised the world by declaring it would dismantle the test site to “transparently guarantee” its dramatic commitment to stop all nuclear and missile tests.

The Punggye-ri site, where North Korea has conducted all six of its nuclear tests, consists of a system of tunnels dug beneath Mount Mantap in the northeastern part of the country.