BAGHDAD, Iraq, Dec. 17, 2011 -- In the end, there was no decisive battle, no peace treaty. The United States' bloodiest conflict since Vietnam ended with a border crossing.
After nearly nine years, $800 billion, 4,500 American dead and an estimated 100,000 Iraqi dead, the war in Iraq is over -- at least for the U.S. military. At just after 7:30 a.m. local, the last U.S. combat troops crossed from Iraq into Kuwait along the same roads the United States used to invade the country in 2003.
One and a half million American men and women served in Iraq since that first force arrived, back when the campaign was expected to be quick and greeted warmly. But even today, the legacy of the war is in many ways still unknown: The United States is leaving an Iraq where sectarian, regional, and political groups still show willingness -- and sometimes a desire -- to resolve their differences violently, and where many of the vital issues created by the invasion are still unsettled.
Saddam Hussein is gone and the country and its armed forces have improved in many ways since the peak of the war, in 2007. But Iraq is still struggling to shake off the weighty baggage of decades of dictatorship and conflict. Many Iraqis are hopeful for the future, but just as many are anxious, as their devastated country faces a power vacuum and an expected explosion of oil wealth and construction projects.
For the United States, a war launched in the aftermath of 9/11 became one of its most controversial. Repeated and extended deployments strained the military and the country's budget.
More recently, because of the costs and struggles of the Iraq war, the United States has changed how it intervenes overseas, shunning large-scale invasions for relatively small interventions that aid local insurgent groups.
Still, today the final commander in Iraq said the war was worth it.
"If you're a loved one of someone that was killed in action or seriously wounded in action, there are no words that can make you ever believe that this was worth it," Gen. Lloyd Austin said today in Camp Adder, from where the final combat troops left.
"However, if you really think about what's happened here -- we removed a brutal dictator that killed, tortured hundreds of thousands of people over time and it provided the Iraqi people opportunities that they have not seen in their lifetime," Austin said. "If you consider the fact that we have a young democracy in a very critical region, a region that's critical to the United States of America -- yes, it was worth it."
Inside the seat of power in Baghdad -- the same heavily fortified Green Zone that the United States made its headquarters after the invasion -- the government expressed thanks for the sacrifices of U.S. troops. But it is struggling with sectarian tensions and a tenuous power-sharing agreement that reflect the fragility of the political process here.
The last combat troops weren't even out of the country before the largest member of the government's coalition pulled out of parliament. The Sunni-backed group Iraqiya said Friday it was suspending participation for two weeks because of a conflict with the Shia prime minister, who has consolidated power by keeping the defense and interior ministry portfolios to himself.
Sectarian issues at senior levels are expected, but if not checked, they can quickly spill into violence at the street level. This week in Diyala province northeast of Baghdad, local Sunni leaders voted to seek autonomy from Baghdad -- and Shia protestors took to the streets. The departure of the Iraqiya bloc from parliament was a form of solidarity with Diyala's local rulers.
Senior officials in the government urge patience. Just because the war is finished, they say, doesn't mean the peace can be built overnight. The wounds of the war are still fresh.
"We are very happy for these young men and women to go back safely. We share their sorrow and grief for the ones who have fallen in Iraq and we do believe that Iraqis, on their own, could not have freed themselves from Saddam's tyranny," Deputy Prime Minister Hussain al-Shahristani said in a weekend interview with ABC News. "The Iraqis will remember all that. But that is not to say that some serious mistakes were not made on the ground. There have been many people, Iraqi people, that have been killed unnecessarily, and of course that has left some sorrow and grief among the Iraqis."
For many in Baghdad, the main concern isn't political instability or even the return of violence. Attacks have become accepted in Iraq right now, to a certain extent -- down 90 percent from the peak of the war, but still as high as a few dozen on a bad day. More of a concern, many resident say, is a lack of basic services.
The electricity service is rated as "bad" or "very bad" by 79 percent of households, according to data released by the United Nations this week. On average, they only receive 14.6 hours of electricity every day, and 90 percent rely on a generator, according to the U.N. Fifty-nine percent say their water and sanitation facilities are "bad" or "very bad," and that number rises to 85 percent in rural areas.
The numbers do not reflect a shoddy electrical grid or poor sanitation infrastructure as much as they reflect Iraqis' booming desires and demands. Analysts say the electricity output since Saddam Hussein was overthrown has doubled -- but demand has tripled.
Part of that is a product of being able to watch satellite TV and go on the Internet for the first time -- two actions forbidden under Saddam Hussein. But if the government cannot quickly deliver on these increased appetites, the hunger could turn into frustration.
In that sense, Iraqis are hungry for more -- a healthy demand despite the psychological scars of the war. But if the government cannot quickly deliver, the hunger could turn into frustration.
In the interview, Shahristani admitted as much, saying that people needed to be patient.
"Things take time," he said.
He argued that life had dramatically improved for many people since the invasion, despite the continuing violence.
"There is a huge difference and people can see that. If you go to a village or a small town or even the capitol you will see people with satellite dishes, with mobile phones and see the number of new cars on the roads," he said.
That success is visible nearly everywhere in Baghdad, and many say it is irreversible. But that doesn't mean that people aren't worried about instability returning.
Dr. Moyad lives in Dorra, a neighborhood that used to be an al Qaeda stronghold. It was also one of the first areas that the United States tried to target Saddam Hussein at the beginning of the war. Moyad braved risks to help the U.S. military when it entered Dorra during some of Iraq's darkest days.
He survived and today he is thriving. He is building a hospital and says other families in the neighborhood are jealous of his success and his closeness with multiple American leaders, including former Iraq commander Gen. David Petraeus.
But even he senses struggle just below the surface. There is not enough electricity to run his hospital, he says. Bureaucracy and outdated laws are preventing him from hiring foreign experts. Corruption is endemic. And he argues there has been no long-term political reconciliation that would allow for the possibility of sectarian strife.
"The government of Iraq is too young and inexperienced to be driving the car of Iraq," he says. "It's a good car, but we do not have a good driver."
Troops Come Home
As the U.S. departed Iraq, a line of more than 100 U.S. vehicles, and nearly 500 soldiers headed out to make history.
Some of the soldiers were on their fourth deployments to Iraq, but many more on their first.
A significant number of the soldiers were just children when the war began.
As the troops crossed the border they were greeted with the rising sun in Kuwait.
"I'm very proud of what we've been able to accomplish since I've been here, and my time here, my first deployment, it's nice to be going home, especially before the holidays," said Specialist David Trudeau.
ABC News' Martha Raddatz contributed to this report.