In 1968 the 2nd Infantry Division was headquartered at Tonggu Ri and responsible for watching over a portion of the DMZ. In 1968 North Koreans continued to probe across the DMZ, and in 1969, while on patrol, four soldiers of 3d Battalion, 23d Infantry were killed. On 18 August 1976, during a routine tree-trimming operation within the DMZ, two American officers of the Joint Security Force (Joint Security Area) were axed to death in a melee with North Korean border guards called the Axe Murder Incident. On 21 August, following the deaths, the 2nd Infantry Division supported the United Nations Command in "Operation Paul Bunyan" to cut down the "Panmunjeom Tree". This effort was conducted by Task Force Brady (named after the 2nd ID Commander) in support of Task Force Vierra (named after the Joint Security Area Battalion commander).