When the Korean War began on June 25, 1950 — exactly 67 years ago this weekend — it sparked a conflict that would simmer long after the war officially ended in armistice in 1953. That long-running tension was the subject of a 1960 examination by LIFE magazine on the 10th anniversary of the war’s onset, which captured one of the “endless series of small but meaningful disputes” along the North-South border in the photographs seen here.

As the article explained, a demilitarized zone (DMZ) of 4,300 yards separated the Communist forces in the North from the U.N. forces in the South, with strict regulations governing what could be allowed inside the buffer area. In this particular instance, U.N. forces had noted “North Korean troops building a suspicious-looking concrete fortress inside the DMZ” and, after a meeting was called to discuss the matter, American representatives were asked to figure out what it was. The North Korean forces refused to allow inspection of the structure, going so far as to hold objects in front of the sight-lines of Americans’ binoculars.

After about an hour of “wrangling,” the photographer reported, the two sides went their separate ways, adding one more item to the list of “unresolved issues” at the border.

Today, nearly seven decades after the DMZ was established, that infamous buffer zone still exists and remains one of the world’s tensest borders.