Iraqi Prime Minister Nouri al-Maliki, a longtime friend of Tehran, has systematically infiltrated his operatives into the country's intelligence services, rebuilt by the CIA after the fall of Saddam Hussein in 2003 as a buttress against Iranian influence.

These services are a crucial component in what is increasingly seen as Maliki's intention to establish himself as the supreme power in Iraq as it drives to become one of the world's energy superpowers.

"The institutionalization of a new Iraqi intelligence apparatus after the fall of Saddam Hussein has been a tumultuous process," observed the U.S. global security consultancy Stratfor.

Since the Americans began reshaping the intelligence services that Saddam had built into the most formidable pillar of his brutal regime, there's been a struggle between the majority Shiites, many of whom lean toward Shiite Iran, and the Sunni minority that was the backbone of Saddam's Baathist regime -- and its security services.

The Americans found, as they had in Germany after World War II, that they needed the experienced operatives of the ousted regime to create new intelligence structures, in 1945 to combat the Soviet Union, after 2003, to counter an expansionist Iran.

They brought back hundreds of Sunni veterans of Saddam's General Security Service and the many other branches of his elaborate intelligence network.

That didn't sit well with the Shiites, who were empowered after Saddam's downfall.

The core of the new system is the Iraqi National Intelligence Service, organized and funded by the CIA, and the Ministry of State for National Security.

The INIS, established in 2004, was initially headed by a Sunni, a former air force general named Mohammed Abdullah Shahwani who defected from Saddam's regime in 1990 and played a key role in an ill-fated, CIA-backed plot to topple Saddam in 1996.

He recruited hundreds of former Baathists, with the CIA's blessing. Many were veterans of Saddam's infamous General Intelligence Directorate, which became Iraq's leading foreign intelligence service, and in particular Department 18, which ran operations against Iran.

When Maliki was elected prime minister in 2006, the dominant Shiites sought to sabotage the Sunni-dominated INIS.

Maliki brought one of Saddam's former generals, Sherwan al-Waeli who after the dictator's fall played an increasingly important role in Maliki's Shiite Ad-Dawa party. He built up a large cadre of supporters within the MSNS and by 2009 has built up a force of 1,500-2,000 intelligence operatives to rival Shahwani's 1,200-strong INIS.

Informed sources say the Maliki-controlled MSNS runs as many as 20,000 personnel, giving the premier, who also controls the defense and interior ministries, power unrivalled since Saddam Hussein's heyday.

The MSNS strength cannot be independently verified. But Stratfor observes the department "has expanded quickly to serve as a regime intelligence service" along the lines of Saddam's Special Security Service.

The SSS, headed by his youngest son Qusai, was established in 1982 as a presidential intelligence service to protect the dictator. It had agents in every other intelligence and security organization in Iraq.

The pro-CIA Shahwani, who resisted Maliki's personal takeover of the security services, resigned under pressure as INIS chief in 2009 after dozens of his men had been killed, either by rival Iraqi organizations or Iran's intelligence apparatus.

Shahwani claims 290 of his officers were killed in 2004-09. Since then "the competition between the INIS and MSNS due to factional allegiances has only grown," Stratfor observes.

INIS officers claim Maliki's regime has issued arrest warrants against another 180. Stratfor reports "500 INIS officers have been killed and 700 imprisoned since 2004.

"The INIS appeared to mount a response in 2009, when Shiite sources within the INIS reported that MSNS personnel also were being assassinated," it said.

"They claim the culprits were the hard-line former Baathist officers reinducted into the INIS."

This internecine warfare is exposing Iraq to untold dangers as it wrestles with persistent security challenges as Iran's influence increases following the U.S. withdrawal.

That could jeopardize Iraq's economic future and its potential energy power.

"Instead of institutionalizing and focusing on threats to Iraq, the intelligence services have been fighting and focusing on threats to the regime," Stratfor noted.

"Al-Maliki and other Shiite leaders will now try to enforce complete authority over all the Iraq's intelligence services but it remains to be seen how well they can perform."