Mines and other booby traps were one of the principal weapons used by the insurgents against Portuguese mechanized forces to great effect, who typically patrolled the mostly unpaved roads of their territories using motor vehicles and armored scout cars. To counter the mine threat, Portuguese engineers commenced the herculean task of tarring the rural road network. Mine detection was accomplished not only by electronic mine detectors, but also by employing trained soldiers ("picadors") walking abreast with long probes to detect nonmetallic road mines.