US soldiers of 1st Squadron, 4th Cava

US soldiers of 1st Squadron, 4th Cavalry on Zippo Tracks armored personnel carriers incinerating Iron Triangle area during Operation Cedar Falls. (Photo by Dick Swanson/Getty Images)

An M132 “Zippo” armored flamethrower of 1st Squadron, 4th Cavalry Regiment, 1st Infantry Division, incinerates an enemy position in the Iron Triangle between Saigon and Cambodia during Operation Cedar Falls in January 1967. (Photo by Dick Swanson/Getty Images)

Photo by Dick Swanson/Getty Images