Iraqi authorities have grown dependent on the U.S. military after more than five years of war. While they are aiming for full sovereignty with no foreign troops on their soil, they do not want to rush. In a similar sense, the Americans fear that after losing more than 4,100 troops, the sacrifice could be squandered.

U.S. commanders say a substantial American military presence will be needed beyond 2009. But judging from the security gains that have been sustained over the first half of this year — as the Pentagon withdrew five Army brigades sent as reinforcements in 2007 — the remaining troops could be used as peacekeepers more than combatants.

As a measure of the transitioning U.S. role, Maj. Gen. Jeffery Hammond says that when he took command of American forces in the Baghdad area about seven months ago he was spending 80 percent of his time working on combat-related matters and about 20 percent on what the military calls "nonkinetic" issues, such as supporting the development of Iraqi government institutions and humanitarian aid.

Now Hammond estimates those percentage have been almost reversed. For several hours one recent day, for example, Hammond consulted on water projects with a Sunni sheik in the Radwaniyah area of southwest Baghdad, then spent time with an Iraqi physician/entrepreneur in the Dora district of southern Baghdad — an area, now calm, that in early 2007 was one of the capital's most violent zones.

"We're getting close to something that looks like an end to mass violence in Iraq," says Stephen Biddle, an analyst at the Council of Foreign Relations who has advised Petraeus on war strategy. Biddle is not ready to say it's over, but he sees the U.S. mission shifting from fighting the insurgents to keeping the peace.

Although Sunni and Shiite extremists are still around, they have surrendered the initiative and have lost the support of many ordinary Iraqis. That can be traced to an altered U.S. approach to countering the insurgency — a Petraeus-driven move to take more U.S. troops off their big bases and put them in Baghdad neighborhoods where they mixed with ordinary Iraqis and built a new level of trust.

Army Col. Tom James, a brigade commander who is on his third combat tour in Iraq, explains the new calm this way:

"We've put out the forest fire. Now we're dealing with pop-up fires."

It's not the end of fighting. It looks like the beginning of a perilous peace.

Maj. Gen. Ali Hadi Hussein al-Yaseri, the chief of patrol police in the capital, sees the changes.

"Even eight months ago, Baghdad was not today's Baghdad," he says.