24 May Los Angeles Times commentary - Securing Baghdad is a Numbers Game by Max Boot.

The U.S. needs at least three more brigades in Iraq's capital...

The inauguration of a coalition government suggests that the situation in Iraq is not as gloomy as some opponents of the war claim. But the aftermath also shows that the situation is not as sunny as some supporters of the war believe...

Supporters of the war note that much of the violence in Iraq is confined to four of 18 provinces. True. But you can't ignore the continuing instability in the capital. Baghdad is much more important to Iraq than Washington is to the United States. With at least 6 million residents, it has a quarter of the country's population, and it is not only the political capital but the center of media, business and culture...

The pacification of Tall Afar, a town of at least 150,000, required 3,800 American and 5,000 Iraqi soldiers. That's a ratio of one American per 40 civilians. In Baghdad, there are currently three American combat brigades, or about 8,600 troops. That's a ratio of one American per 698 civilians. No wonder the capital is so unsafe.

Even if you add in Iraqi security forces — about 9,000 Iraqi soldiers and 12,000 national police officers are deployed in Baghdad — there is still a woeful shortage of security. The problem is compounded by the fact that many of the uniformed Iraqis belong to political militias, criminal gangs or insurgent groups. Residents don't know whom to trust.

To gain control of the situation, an American officer who has served in Baghdad suggested to me the need to deploy at least 35,000 U.S. troops (six brigade combat teams, plus support personnel), two Iraqi army divisions (20,000 men), and 30,000 competent Iraqi police officers. That would give you a total of 85,000 security personnel, or one per 71 inhabitants — still lower than the ratio in Tall Afar but much higher than it is today...