Who are the bad guys in Iraq?

Dan Gifford's son, who just had a tour of duty in Iraq, had a lot of interesting things to say about his time there. Here is one of the facts that he mentioned:

"Most of the carnage is caused by the Zarqawi Al Qaeda group. They operate mostly in Anbar province (Fallujah and Ramadi). These are mostly "foreigners", non-Iraqi Sunni Arab Jihadists from all over the Muslim world (and Europe). Most enter Iraq through Syria (with, of course, the knowledge and complicity of the Syrian govt.) , and then travel down the "rat line" which is the trail of towns along the Euphrates River that we've been hitting hard for the last few months. Some are virtually untrained young Jihadists that often end up as suicide bombers or in "sacrifice squads". Most, however, are hard core terrorists from all the usual suspects (Al Qaeda, Hezbollah, Hamas etc.) These are the guys running around murdering civilians en masse and cutting heads off. The Chechens (many of whom are Caucasian), are supposedly the most ruthless and the best fighters. (they have been fighting the Russians for years). In the Baghdad area and south, most of the insurgents are Iranian inspired (and led) Iraqi Shiites. The Iranian Shiia have been very adept at infiltrating the Iraqi local govt.'s, the police forces and the Army. The have had a massive spy and agitator network there since the Iran-Iraq war in the early 80's. Most of the Saddam loyalists were killed, captured or gave up long ago."