Internationally isolated and fearful of losing power, former Iraqi president Saddam Hussein made an astonishing move in the last years of his secular rule: He invited into Iraq clerics who preached an austere form of Islam that's prevalent in Saudi Arabia.
He also let extremely religious Iraqis join his ruling Baath Socialist Party. Saddam's bid to win over devout Muslims planted the seeds of the insurgency behind some of the deadliest attacks against US and Iraqi forces today, say Saudi dissidents and US officials.
"Saddam invited Muslim scholars and preachers to Iraq for his own survival," said Saad Fagih, a London-based Saudi dissident. "He convinced them that Shiites are the danger."
Shiite Muslims make up about 60 percent of Iraq's 26 million people and they strongly support planned Jan. 30 elections, hoping to reverse the longtime domination of Iraq's Sunni minority. The insurgency is thought to be run mostly by Sunnis who fear losing power.
Saudi Arabia's Wahhabi -- or Salafi -- brand of Sunni Islam began trickling into Iraq in the mid-1990s, at the height of punishing international sanctions for Saddam's invasion of Kuwait.
A Wahhabi mosque was even built in the Shiite holy city of Karbala at a time when Shiites were banned from worshipping their religion freely.
The words "God is great" were added to the Iraqi flag after Saddam's defeat in the 1991 Gulf War. He closed bars and nightclubs to appease Muslims.
Around the same time, several militant Islamic groups, including Jund al-Islam (Islam's Soldier), started taking root in the mountains of northern Iraq along the Iranian border.
After the Sept. 11, 2001 attacks on the US, these Salafi groups reorganized under Ansar al-Islam, which had ties with Osama bin Laden's al-Qaeda and with Jordanian militant leader Abu-Musab al-Zarqawi, a leader of the current insurgency.
Ansar al-Islam, which adhered to a rigid Salafi ideology, seems to have been destroyed during the initial days of the US-led invasion when its bases were attacked by US forces in March 2003.
There's no question, however, that Saddam invited Islamic extremists into Iraq.
The core insurgency is Iraqi Sunni Muslims -- a volatile mix of groups and freelancers who include loyalists of the former Baath Party, Fedayeen militiamen, former Republican Guard and intelligence agents, Islamic extremists, paid common criminals and disaffected Iraqis.
The Sunni resistance at first wanted to use al-Zarqawi as a tool to draw support for their cause, according to Fagih, who maintains contacts in Saudi Arabia.
"Foreigners came and were ready to kill themselves," he said, but the Sunni resistance discovered it couldn't control al-Zarqawi. "He's like an unguided missile."
Now, US officials say it is local insurgents -- essentially former regime elements and Islamic extremists, and not foreign fighters -- who are proving difficult to defeat.
"If in Iraq there were only al-Zarqawi or al-Qaida, the situation would be manageable," a US government official based in Iraq said on condition of anonymity. "It would be just like any country with terrorist problems. Al-Zarqawi and al-Qaeda wouldn't have the effect of what we are seeing now."