original_query: When did the North Korean soldiers cross the Demilitarized Zone and fire on South Korean positions?
query: When did North Korean soldiers cross the Demilitarized Zone and fire on South Korean positions?
answer: North Korean soldiers crossed the DMZ and fired on South Korean positions on multiple occasions.  Specific dates include April 1997 (in Cheolwon, Gangwon-do) and June 1997 (70m south of the center of the DMZ).