Between 1968 and 1972, the Portuguese forces increased their offensive posture, in the form of raids into PAIGC-controlled territory. At this time Portuguese forces also adopted unorthodox means of countering the insurgents, including attacks on the political structure of the nationalist movement. This strategy culminated in the assassination of Amílcar Cabral in January 1973. Nonetheless, the PAIGC continued to increase its strength, and began to heavily press Portuguese defense forces. This became even more apparent after the PAIGC received heavy radar-guided anti-aircraft cannon and other AA munitions provided by the Soviets, including SA-7 shoulder-launched anti-aircraft missiles, all of which seriously impeded Portuguese air operations.