Krim joined the underground Algerian People's Party at the beginning of 1946, setting up clandestine cells in 12 villages around Draa el-Mizan.

[1] Accused of the murder of a forest warden in 1947, he was hunted and he joined the maquis under the Pseudonym of Si Rabah with Moh Nachid, Mohand Talah and Messaoud Ben Arab.

Twice sentenced to death by French tribunals in 1947 and 1950, he became the Kabylie responsible of the PPA-MTLD paramilitary organization founded in February 1947 by Messali Hadj, the Organisation spéciale, at the head of 22 members of the resistance (maquisards).

Belkacem was in opposition to the creation of the Political Bureau of the FLN in July 1962 by Ahmed Ben Bella, Houari Boumédiène, and Mohamed Khider.

On October 17, 1967, he created with friends including Slimane Amirat, Colonels Amar Ouamrane and Mohand Oulhadj, the Movement for the Defense of the Algerian Revolution (MDRA), an underground party intended to fight against the Boumediene regime.