How do you make up after a 70-year breakup? It’s not easy.

South Korea says it has been in talks with North Korea and the United States to formally end the 1950-53 Korean War, which was halted by an armistice, or truce, rather than a negotiated peace treaty, which means that the fighting ended, but the war did not.

The prospects of such a deal are still unclear. While the outlines of a peace accord have been considered for decades, there are drastic differences this time. President Trump’s announcement that he would meet with Kim Jong-un, the North Korean leader, could lead to the first-ever direct meeting between leaders of the two countries.

But first Mr. Kim will meet with President Moon Jae-in of South Korea this Friday in the Demilitarized Zone that divides their countries. The South’s declaration that a deal to end the war formally is under consideration has raised expectations for their meeting.