Mujahedin-e Khalq Organization
http://www.ict.org.il/inter_ter/orgdet.cfm?orgid=24
a.k.a: The National Liberation Army of Iran (NLA, the militant wing of the MEK, The Peoples Mujahedin of Iran (PMOI), National Council of Resistance (NCR), Muslim Iranian Students Society (front organization used to garner financial support)
Originally formed in the 1960's as an armed Islamic opposition movement against Shah Mohammad Reza Pahlavi, the MKO fought in the guerrilla operations that forced his overthrow. However due to its radical socialist ideology the organization was cut out of the power structure built by the ayatollahs in the wake of the revolution.
The group turned against the new government and continues to wage an armed struggle against the Iranian state from Iraq, which provides the group with financial and logistical support and military equipment. The MKO remains the most powerful opponent of the Islamic Republic, attacking targets in Iran and assassinating Iranian officials. It is generally believed to have 15 to 20 bases in Iraq.
The MEK was founded in 1965 after a split in a Marxist-Leninist movement that had waged a guerrilla action in northern Iran. Its ideology emerged as a mix of Islam and Marx, with ingredients from the Iranian religious sociologist Ali Shariati, who advocated an "Islam without a clergy." The MEK, with KGB help, engaged in a campaign against the Shah, and sent cadres to Cuba, East Germany, South Yemen and Palestinian camps in Lebanon to train as guerrillas.
Vladimir Kuzishkin, a former KGB head in Tehran, reveals in his memoirs that the MEK became a major source of information on Iran for Moscow. It also helped Moscow in its efforts to thwart U.S. influence in Iran. In 1970 and 1971 the MEK murdered five American military technicians working with the Iranian army. An MEK team tried to kidnap U.S. Ambassador Douglas MacArthur III in Tehran. The attempt failed and their leader, Rajavi, was handed a death sentence, later commuted thanks to a plea to the Shah from Soviet President Nikolai Podgorny.
http://www.benadorassociates.com/article/435