The Iraqi government has taken a lot of criticism from the public this year because of the increase in terrorist violence. Nearly all of this is from Sunni terrorists, with Saddam diehards, Sunni nationalists, and al Qaeda accounting for most of the violence. The government calls them all "al Qaeda" and claims to have killed or captured 40 percent (70 individuals) of the terrorist leadership so far this year. To back up this claim the government points to the fact that terrorism related deaths fell by half last month, to 164, compared to July (when 325 died compared to 282 in June). The government also pointed to the large number of terrorist-related arrests (of lower level killers) in the last month. Then there is the poor quality of many recent terrorist attacks and the growing number that are aborted by police intervention or a poorly made bomb not going off (or exploding prematurely). Then there is the growing number of terrorist attacks against the security forces, in an obvious effort to get the police and soldiers to back off. This works in some parts of the country but in most areas the security forces take the attacks personally and consider the terrorists a deadly enemy who must be killed before they can attack anymore cops and soldiers.
For its part, al Qaeda boasted of carrying out 131 attacks during Ramadan (July 21 through August 18). Islamic radicals consider it particularly pious to kill enemies of Islam during the holy month of Ramada. In this case the terrorists were careful to point out that most of the 131 attacks were directed at the security forces and members of pro-government militias. Iraq is now a democracy and al Qaeda considers democracy anti-Islamic.
The recent sharp decline is the result of several other factors. First, the Sunni terrorist groups could not sustain the level of violence they began in January (when 225 victims died). Second, pressure from the government (in reaction to public anger) produced more tips from citizens, more neighborhood self-defense groups, and more effective performance by the police. Third, some Sunni Islamic terrorists (mainly foreigners) have gone to fight in Syria, where the Sunni majority is rebelling against the Shia minority dictatorship. The feeling is that, at the very least, Sunni terror groups will have sanctuary in Syria once the Shia government is overthrown. That would enable the Sunni terrorists to use Syria as a base for continued attacks on the majority Shia government of Iraq.
Finally, the Sunni terrorists have cut back on their bombing attacks and switched to more assassination operations against police and military commanders. This is an effort to get the security forces to back off on their efforts to wipe out Sunni terror groups. This sort of thing requires less manpower and can often be contracted out to professional assassins (of which there were always a lot of in Iraq). The Sunni terrorists are aware that their attacks on Shia civilians are unpopular with many Sunnis because in the past this kind of violence led to a major campaign by Shia terrorist groups (who have been quiet lately) against Sunni civilians.
The assassination campaign is one of the main reasons the police leadership is so poor and corrupt. When you are spending most of your time just trying to stay alive, job performance suffers. And it's not just Islamic terrorists coming after you, there are also gangsters looking for some cooperation or trying to get you to switch loyalty from another gangster. This is why curbing corruption is so important, as it is the source of most problems in the country.