Composed of locally recruited men, often former guerrilla fighters but mostly bushman Khoisan, the units specialised in reconnaissance, tracking, unconventional tactics, and pseudo-terrorist operations.

[3] The Flechas were created and organized by Sub-Inspector Oscar Cardoso, when he was the head of the PIDE branch at Serpa Pinto, Angola (present day Menongue).

General Costa Gomes – Portuguese Commander-in-Chief in Angola – argued that African soldiers were cheaper, knew the terrain better, and were better able to create a relationship with the local populace, a tactic that predates the 'hearts and minds' strategy later used by United States forces in Vietnam at the time.

Flechas units were also created and operated in Mozambique at the very end stages of the conflict, following the dismissal of Kaúlza de Arriaga on the eve of the Portuguese coup in 1974.

They also frequently used captured AK-47 rifles and they showed a special preference for the use of tribal traditional weapons, including spears and the bows and arrows which gave origin to the name of the unit.