The Shadow PMC is an enemy faction existing of american and russian mercenaries, working to protect an HVT. They appear in Warzone: Iron Wolf and are disbanded and established into the newly formed anti-american group Typhoon. They were hired by Krazny to protect Agent: Sagitarrio. They only appear in the mission Sagitarrio.
The Shadow PMC is a group of american and russian mercenaries paid by Roman Marshikov, a Krazny topman, to pay his debt to defected agent: Sagitarrio. They are located on Malta, mainly the urban district of Valetta. The PMCs use civilian supplies from multiple regions in Russia, but also civilian weapons to bypass Maltese security and keep off the grid.
On the day of the Task Force 121's raid of Sagitarrio's compound, it is likely that all members of the Shadow PMC guarding were killed. If they had survived, it is likely they became high-ranking Typhoon members.