Born of the US occupation of Iraq, the soldiers of the Islamic Army pride themselves on being Iraqis, and say that their main aim is to expel foreign powers from the country, Al Jazeera's Iraq correspondent reports.
Three years after the invasion, the armed group is still waging its campaign against US troops.
Its actions are carried out around Baghdad, but are mainly focused on the western province of Al-Anbar, an area the coalition forces are unable to control despite numerous military operations.
Branded by many as insurgents, or terrorists, the Islamic Army describes itself as a national resistance movement and guarantees that there are no foreigners within its ranks.
Ibrahim al-Shamary, a spokesman for the Islamic army in Iraq, told Al Jazeera in an exclusive interview: "There are two occupations in Iraq. Iran on one side through the militias which they control and through direct involvement with the national guard and the intelligence services, that causes the killing and destruction of the Sunnis.
"And then there is the American occupation which destroys the Iraqi people."
The group became known for its grizzly videos of kidnappings and attacks on foreign and Iraqi troops, a powerful tool of intimidation that led many businesses to leave Iraq.
Reconstruction has since slowed down and some foreign troops have pulled out.
These group says it is protecting Iraqis from the brutality of a foreign occupation.
Al-Shamary said: "The occupation is hiding lots of crimes; when they leave, the world will see the full picture."
"The occupation is hiding lots of crimes; when they leave, the world will see the full picture"
Ibrahim al-Shamary, a spokesman for the Islamic army in Iraq
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With the current chaos in Iraq, there is no shortage of recruits.
New recruits train in the art of war among the palm groves on the outskirts of Baghdad.
During the two-week intensive course in guerrilla warfare they learn the tactics of ambushes - and kidnappings, with the help of local residents who act out the part of the victim.
They also recieve instructions on how to hit US helicopters, conduct rescue operations and carry out heavy artillery assaults.
"The fighters sacrifice their lives to protect the people," a- Shamary said.