Operation Prairie was a U.S. military operation in Quảng Trị Province , South Vietnam that sought to eliminate People 's Army of Vietnam ( PAVN ) forces south of the Demilitarized Zone ( DMZ ) .

Operation Prairie was conceived Creating as a larger , longer mission covering the same areas along the DMZ .

The smoke generated Creating by the fires Catastrophe was blown Motion into the Prairie Provinces and created Creating a moderate health risk Catastrophe there leading Causation Environment Canada to declare Expressing_publicly an air quality advisory Warning for southern Saskatchewan and Manitoba on 9 July .