There are concerns that the security crackdowns in Baghdad and Al-Anbar may be pushing militants to carry out attacks in other parts of Iraq -- including ethnically and religiously mixed areas north of the capital.
The mixed city of Mosul, about 360 kilometers northwest of Baghdad, is one example.
While militant attacks in Al-Anbar and Baghdad have decreased since the summer, Mosul has seen a rise in violence. Many blame that violence on an influx of militants fleeing operations related to the U.S. troop increase.
Police checkpoints in Mosul are coming under attack from gunmen, and the threat of suicide bombers is ever present. In one recent attack, Islamic militants killed a woman who ran a beauty parlor in her home -- apparently angry at what they see as a violation of Islamic tradition.
Mosul's chief of police, Major General Wathiq al-Hamdani, recently told Radio Free Iraq that militants have been trying to infiltrate the city because of surge operations elsewhere.
"Following the implementation of security plans in Baghdad, Diyala, and Al-Anbar, some of the terrorists have indeed fled to Mosul," al-Hamdani said. "But we have had plans in place since before Ramadan to confront them. They have not been able to sneak in in large numbers. To the contrary, we have them pinned down in certain areas where we are carrying out operations against them. For example, we [recently] arrested 37 of them [in a single day] -- including two leading operatives of Al-Qaeda."
Military 'Surge,' Insurgent Campaign
Meanwhile, the religiously and ethnically mixed Diyala Governate is an example of an area where militant violence has increased despite the increased troop deployments there.
Stretching out from the northeast of Baghdad, the governorate spans the Tigris and Diyala rivers and spreads east to the Iranian border. Surge operations there have had to deal with Sunni Al-Qaeda-linked militants as well as Shi'ite militia fighters.
During the first week of December alone, more than 60 people were killed and 90 injured by five major bombing and shooting attacks in Diyala.
That violence follows the release on an insurgent website of an audio recording thought to be of Abu Omar al-Baghdadi -- the leader of the Al-Qaeda linked group Islamic State in Iraq. The message calls on militants to launch a campaign against foreign troops and Iraqi government forces.
"This campaign should be based on explosives and its target should be the infidels -- those wearing military uniforms and distinctive clothes and all those who fight alongside the occupiers," al-Baghdadi says. "Every [militant] must detonate at least three bombs by the end of the campaign -- ranging from hand grenades to booby traps."
Iraqi Defense Ministry spokesman Muhammad al-Askari rejects the notion that Al-Qaeda-linked militants are regrouping and proliferating. Rather, he says al-Baghdadi's message reflects the desperation of militants.
"Terrorists are trying to do something in order to prove that they still exist," al-Askari said. "The escalation in question has not been serious and it is not the norm. We think it is a reaction by the terrorists to say they are still there. This escalation will end in the near future."
Analysts say Sunni militants linked to Al-Qaeda also may be trying to again foment sectarian violence in Diyala Governorate and Mosul because local Sunni tribal leaders have turned against them in Baghdad and Al-Anbar Governorate.
Jim Denselow, an expert on Iraq and defense issues at the London-based think tank Chatham House, said the U.S. military has been very successful in using Iraqi forces against Al-Qaeda in Iraq and other insurgent groups. "They've co-opted a large amount of the Sunni insurgency," Denselow said. "They've turned lots of these groups against the foreign fighter elements and Al-Qaeda in Iraq, which has seen its power base decline ever since the death of its nominal leader," Abu Musab al-Zarqawi, in 2006.
The U.S. commander in Iraq, General David Petraeus, told the U.S. Congress in September that Sunni Islamist militants from Al-Qaeda in Iraq appear to have been squeezed out of Al-Anbar Governorate by the troop increase.
Petraeus attributes that development not only to the efforts of U.S.-led coalition forces, but also to an increasing number of Sunni tribal leaders and militants in Al-Anbar who have turned against Al-Qaeda in Iraq.
"The most significant development in the past six months likely has been the increasing emergence of tribes and local citizens rejecting Al-Qaeda and other extremists," Petraeus said. "We engaged in dialogue with insurgent groups and tribes. And this led to additional elements standing up to oppose Al-Qaeda and other extremists. The tribal rejection of Al-Qaeda that started in Anbar Province and helped produce such significant change there has now spread to a number of other locations as well."
Meanwhile, the commander of U.S. Marines in western Iraq says the security gains made in Al-Anbar Governorate during the past year are permanent.
Major General Walter Gaskin says there is now a "schism" between Al-Anbar's Sunni tribes and Sunni militants from Al-Qaeda in Iraq. He says Sunni militants have alienated Al-Anbar's local tribes with their harsh interpretation of Islam, and by treating local Sunni tribal leaders poorly.
(Radio Free Iraq correspondent Abdelilah Nuaimi contributed to this report)