By 1972 there was growing pressure from other commanders , particularly Kaúlza de Arriaga 's second in command , General Francisco da Costa Gomes , for the use of African soldiers in Flechas units . Flechas units ( Arrows ) was also employed in Angola and was units under the command of the Portuguese PIDE . Composed of local tribesmen , the units specialised in tracking , reconnaissance and anti @-@ terrorist operations .