WASHINGTON -- In January, when President Bush announced his plans to reinforce American troops in Baghdad, Shiite militias were seen as the main worry. Some analysts predicted that bloody clashes with Shiite militants in the Sadr City district in northeastern Baghdad were inevitable.
Instead, during the early weeks of the operation, deadly bombings by Sunni Arab militants have emerged as a greater danger. In particular, the threat posed by the Sunni group al-Qaida in Iraq was underscored when American troops seized a laptop computer from a senior operative in the group who was reported killed in late December.
Information from captured materials indicates that the group's leadership sees "the sectarian war for Baghdad as the necessary main focus of its operations," according to an intelligence report that was described by American officials.
At the same time, the group has continued waging attacks in Anbar province on American troops and on Sunni Arab tribal leaders who have defied it.
Reflecting concern over the group's bomb attacks, especially car bombings, American military officials have begun to emphasize that bringing security to the Iraqi capital will involve not only the protection of Baghdad neighborhoods, but also the use of raids to shut down bomb factories and uncover arms caches in the largely Sunni areas on the outskirts of the city.
"The Baghdad belts are increasingly seen as the key to security in Baghdad," Lt. Gen. Raymond T. Odierno, the American officer in charge of day-to-day operations in Iraq, said in an e-mail message. "I believe this is where you can stop the accelerants to Baghdad violence. We have already found a large number of significant caches in these areas related to car bombs and IEDs," or improvised explosive devices, commonly known as roadside bombs.
"The Shia have gone to ground for the most part, but there are still rogue elements of Shia extremists that are still a threat and conducting operations against the coalition, but more importantly against the government of Iraq," he added.
The threat has shifted on the eve of the fourth anniversary of the war in Iraq, in which American forces toppled Saddam Hussein only to face a growing insurgency and find themselves involved in an arduous effort to head off growing sectarian strife. In its efforts to stabilize Iraq, American commanders have had to contend with al-Qaida in Iraq, other Sunni Arab insurgent groups, a variety of Shiite militias, criminals, and, they say, Iranian operatives. The greater Baghdad area seems to include all of them, making the mission there one of constant adjustment to adversaries who are themselves revising their tactics.
According to American intelligence analysts, al-Qaida in Iraq's Baghdad strategy has gone through several changes. The overwhelming majority of the group's members are believed to be Iraqi. But some of its senior commanders are foreigners, including Abu Ayyub al-Masri, an Egyptian who became the leader of the organization last year after the death of Abu Musab al-Zarqawi, the Jordanian who founded the organization.
The group has been active in Sunni-dominated Anbar province in western Iraq. But it has also long operated in the Sunni areas on the outskirts of the capital. Saddam Hussein encouraged the settlement of Sunnis in these areas in the hope that it would protect his government, and some towns and rural communities there have emerged as havens for Sunni militants.
In the summer and fall of 2006, the group's leaders saw an opportunity to step up the fight in Baghdad against Shiite militias, American troops, and the nascent Iraqi security forces, according to captured documents. Some of the insight into the group's strategy was obtained from a captured laptop computer, which was acquired when a senior Iraqi adviser to Masri was killed by coalition troops in late December at a traffic checkpoint.
The adviser, who among other aliases used the nom de guerre Abu Hasan, had previously been detained by coalition forces in January 2005 but was inadvertently released because his role in al-Qaida in Iraq was not well understood at the time.
As outlined in the captured documents and other material that was seized, the group's initial strategy was to push Shiites out of western Baghdad. As part of the sectarian battle for the capital, the strategy also called for attacking Shiites in nearby provinces, specifically southern Salahuddin, western Diyala, and eastern Anbar, attacks that the group's leaders also calculated would put American and Iraqi troops on the defensive. (The documents, American officials say, also reflected a continued an interest in obtaining chemical weapons.)
But Shiite militias, particularly Mahdi Army operatives, responded with their own offensive, forcing the Sunni militants to retreat. A Pentagon report to Congress noted in November that the main Shiite militia group, the Mahdi Army, had replaced al-Qaida in Iraq "as the most dangerous accelerant of potentially self-sustaining sectarian violence in Iraq." American forces, instead of withdrawing from the capital as the Sunni insurgents had hoped, prepared plans to reinforce their troops there.
According to captured memos portrayed in American intelligence reports and dated early December, the group was frustrated with the Shiite militias' success, was unhappy with weapons shortages, and was somewhat disorganized, according to an account by an American official who asked not to be identified because he was discussing intelligence materials.
As a result, the organization adjusted its tactics. It began to rely more on the Sunni enclaves on the outskirts of the capital. Senior leaders rotated through directed operations from these areas while lower-level fighters operated inside the capital.