Formed in 2004, the group's stated aim is to drive all foreign soldiers out of Iraq.
Dozens of attacks
It is not clear how many fighters the group has, but it claims to have been responsible for dozens of attacks on US forces in northern Baghdad.
Al Jazeera, however, cannot independently verify Jami's claims.
Now, alongside its military campaign, it has launched a propaganda war to get its message across.
Over the years, Jami has established itself as a resistance group which publicly condemns attacks on Iraqi security forces and random targeting of Shia civilians.
Its media centre is run by fighters who each hold a masters degree in media, Al Jazeera has been told.
A Jami media officer told Al Jazeera: "We want to show the West our suffering and we want to show that the Iraqi resistance is not about the killing of Iraqis and terrorism.
"We want them to understand the situation here and see that we are only fighting occupation forces."
For Jami, the most convincing recruitment tools are pictures of abuse by US forces.
The group's field of operations covers the provinces of Anbar, Salahedin, Diyala and around Mosul in the north.
Of late, the US and Iraqi governments have taken advantage of a wave of popular anger that has chased al-Qaeda from its strongholds, to claim a small victory against the "insurgency".
But groups such as Jami will have to be dealt with by other means.
In the absence of Iraqi security forces, they provide security by setting up checkpoints in the areas under their control.
They make sure no stranger enters those areas and establish friendly relations with residents.
In return, the fighters get full support.
The US has not yet to acknowledge their existence as a political force.
|Jami says it wants to show that resistance is|
not about the killing of Iraqis and terrorism
Mohamed Ayash, the head of Iraqi Scholars' Council, says: "There is a big deal of development in the political and military wings of the resistance.
"It now has a political council with a clear agenda.
"George Bush mentions al-Qaeda as his only enemy, he doesn't refer to Iraqi resistance groups.
"But they will continue their attacks on American soldiers."
Ending the fight in Iraq will have to include real negotiations with Jami and the rest of the Iraqi resistance.
So far, none of the plans for national reconciliation includes this vital step.