Operation Paul Bunyan was a countermeasure taken by the United States Army Corps of Engineers in response to an unprovoked attack by North Korean soldiers in the Korean Demilitarized Zone.
On 1976-08-18, a group of United States soldiers and South Korean workers were sent out into the DMZ to trim a poplar tree that was obstructing the view of an observation post. They met resistance from a North Korean patrol who attacked resulting in the death of two U.S. soldiers. As a result, Operation Paul Bunyan was organized and carried out on August 21 involving members of the United States Army Corps of Engineers and supporting infantry which successfully cut down the tree.
This incident led to increased tensions along the Korean Demilitarized Zone, but did not lead to full-scale war.