Mujahadin-e Khalq (MEK), an Iranian opposition group backed by Iraq (and with camps in Iraq) of doing Iraq's dirty work inside Iraq. The MEK is accused of sending their combat units to fight rebellions Kurds and Shiites inside Iraq. The report says this has been going on since 1991. The MEK set up shop in Iraq in 1987.
A US report says the People's Mujahadin, also known as the