Kasim Tariq was one of the agents in Al-Qaeda.
In Yemen in 2001 Michael worked with Kasim. Kasim gave him a list of the people who killed the soldiers of the US Navy. Later when Michael entered the base Kasim killed Michael's wife, Elizabeth and daughter, Hayley.
In "One Way" Percy sent Michael in Uzbekistan to find Kasim. After Nikita and Michael teamed up, they found Kasim's house. They tried to kill him, but his men shot Michael. He had a vest, so he was fine. Kasim thought that Timur Ahmedov betrayed him, so he killed him. Kasim took Michael with him so that he can question him. Kasim was seen later on the airport. Michael tries to stop him, but the security stopped Michael.
In beginning of episode "Covenant", Michael forces Nikita to flush out Kasim. Later it's revealed Kasim was a Division Agent in undercover, and that the bomb wasn't meant for killing Michael's family, it was meant for Michael. Kasim told Michael the bombing was orders from Percy himself. In doing so, Kasim would insinuate himself into Al-Qaeda as a double agent. But eventually, Kasim realized that Percy was not a man of honor and defected from Division. Michael was shocked of hearing of Percy's involvement, so Nikita killed him instead.