North and South Korean troops briefly exchanged gunfire Sunday across the Demilitarized Zone separating the two Koreas. It was the first skirmish at the DMZ since North Korean troops fired on a defector in 2017. This came days after North Korean leader Kim Jong-un appeared publicly Friday for the first time in almost three weeks, touring a newly completed fertilizer factory near Pyongyang. Kim’s appearance followed weeks of speculation about his health and put an end to rumors he was gravely ill after surgery.