ostensibly to stop Process_end these raids Attack , but also to disrupt Hindering the growing alliance between the sadf and the national union for the total independence for angola ( unita ) , which the former was arming Hold with captured plan equipment , the soviet union backed the people 's armed forces of liberation of angola ( fapla ) through a large contingent of military advisers and up to four billion dollars ' worth of modern defence technology in the 1980s .