He was an activist in the Pashtun Tahafuz Movement (PTM), as well as the chairman of a civil society organization, Youth of Waziristan (YOW).
Following the Pakistan Armed Forces' Operation Zarb-e-Azb against militants in June 2014, which forced many residents of North Waziristan to flee their homes and settle at IDP camps in Bannu and other districts, Noor Islam campaigned for the return of the refugees to their homes and organized several protest gatherings against human rights violations in the region.
The North Waziristan police chief, Shafiullah Gandapur, said that a case had been registered against "unknown individuals" and that an investigation about the targeted killing was under way.
[16] The murder caused widespread panic among the locals, who demanded the government of Pakistan improve the law and order situation in the area.
[13] On 30 August, the Pashtun Tahafuz Movement and members of the Youth of Waziristan protested against the killing in Mirali, and demanded the government to punish the murderers.
"[8] In an opinion article for The Diplomat, Mohsin wrote that Noor Islam became "the first active political worker with a profile to match to be killed in a targeted attack since Operation Zarb-e-Azb, the 2014 government military offensive against militant outfits.