However, the railway will not become a reality if U.S.-led sanctions against North Korea persist. Officials had to obtain United Nations approval just to hold Wednesday’s ceremony since it required transporting vehicles across the border to the North Korean border town of Kaesong.

U.S. President Donald Trump signed a peace pledge with North Korean leader Kim Jong Un last summer, where Kim promised to “work toward complete denuclearization of the Korean peninsula,” but details of the agreement were vague, and actual moves towards denuclearization seem to have stalled.

Despite the international concerns over the North’s weapons program, Kim and South Korean President Moon Jae-in have moved towards cooperation over hostility lately, with the railway representing a literal and figurative link between the nations.

“The railways will not only reduce time and space but also the distance between the hearts of the South and North,” South Korean transport minister Kim Hyun-mee said at the ceremony, according to PBS News.

Officials conducted a joint survey of North Korean railways this past fall (a trip that also required U.N. approval), with experts saying the northern rail lines will require a massive amount of investment to update. Reports say Seoul plans to conduct further surveys of North Korean railways and roads before creating a detailed blueprint.

“Actual construction will be pursued in accordance with progress in the North’s denuclearization and the state of sanctions against the North,” South Korea’s Unification Ministry said in a statement, according to the Associated Press.

Government officials and relatives separated by the 1950-53 Korean War were present at Wednesday’s ceremony, along with Russian officials, China’s ambassador to South Korea, and the executive secretary of the U.N. Economic and Social Commission for Asia and the Pacific.