Last Friday's meeting between South Korean President Moon Jae-in and North Korea's leader Kim Jong Un was a historical moment. Kim's steps onto South Korean soil were an extraordinary sight, embodying the diplomatic process that preceded the visit — tentative, but forward moving — as well as a likely anticipation of what will follow — unexpected retreat as Kim and Moon stepped back into North Korea, which was followed by a resumed journey into the South. The key to success is remaining fixed on ultimate objectives and moving toward them, gradually, but inexorably, together, so that an irreversible reversal is impossible.

There was symbolism aplenty in Friday's meeting. The two leaders planted a tree together, using soil from both countries and watered it with water from a river in each country. They sat at a newly refurbished table in the Peace House of the Demilitarized Zone that measures 2,018 millimeters wide at the center to commemorate the year of the meeting. Their chairs were decorated with a carving of a unified Korean Peninsula. Dinner featured food from the hometowns of each of the three South Korean presidents who met their North Korean counterparts, as well as rosti — a traditional Swiss fritter — to remind Kim of his school days in Switzerland. The meal ended with a mango mousse dessert, whose bright colors evoked the arrival of spring, a symbol of the breakthrough in inter-Korean relations, with a silhouette of the Korean Peninsula overlaid upon it.

The Panmunjom Declaration, issued at the end of the meeting, was not as detailed. Among its provisions, it called for: a formal end of the Korean War by yearend; joint efforts toward the "common goal" of denuclearization; establishment of a "joint liaison office" in the Kaesong region; "more active cooperation, exchanges, visits and contacts at all levels"; a visit by Moon to Pyongyang later in the year; and resumption of reunions for families separated by the Korean War.