"On my orders, coalition forces have begun striking selected targets of military importance to undermine Saddam Hussein's ability to wage war," U.S. President George W. Bush told Americans on March 20, 2003. "These are opening stages of what will be a broad and concerted campaign."
The aerial bombing -- dubbed "shock and awe" by U.S. leaders -- immediately phased into ground operations as U.S. and British troops swept across the Kuwaiti border into Iraq.
By April 9, 2003 -- less than three weeks after the military operations began -- U.S. troops were in Baghdad pulling down a statue of the fallen Iraqi dictator.
In the four years since, Hussein has been captured, convicted of mass killings of Iraqis during his brutal rule, and executed.
"The fate of Saddam and his aides is a lesson for everyone," Abd al-Aziz al-Hakim, leader of the most powerful Shi'ite Islamist bloc in the Iraqi government, said in November 2006, immediately after Hussein's conviction on charges of crimes against humanity. "All tyrants, no matter how arrogant they are, will get what they deserve at the hands of those who suffer injustice in this life and the hereafter."
Hard Road To Peace
But despite this and other milestones -- including Iraq's first democratic parliamentary elections in December 2005 -- Iraq has yet to find peace again.
An insurgency by Hussein-loyalists that began in earnest just months after the invasion soon evolved into a guerilla war joined by Al-Qaeda, other Islamic militant groups, and self-declared nationalists.
The insurgency remains most active in the Sunni Arab community -- the power base of Hussein's regime. Their resentment has grown over the majority Shi'ite community's rise to power in elections.
Today, new dangers are emerging as militant Sunni and Shi'ite groups attack each other. Their tit-for-tat violence, which has become daily since the February 22, 2006, bombing of a Shi'ite shrine in Samarra, raises the risk of wider civil war if not contained.
"Putting Iraq above personal and sectarian agendas will be critical as Iraqi leaders and the Iraqi people grapple with some very tough issues in the months ahead," the U.S. commander in Iraq, General David Petraeus, said earlier this month. "If they can do this, and again, I believe they can, Iraq's leaders will be honored as the founding fathers of the new Iraq, and Iraq's citizens will be respected as a wise and courageous people."
Baghdad Security Crackdown
Washington is now basing its efforts to rein in the violence on a joint U.S.-Iraqi security crackdown in Baghdad and restive Al-Anbar Governorate.
For the crackdown, Washington is progressively adding more than 20,000 troops to the some 130,000 U.S. soldiers already in Iraq.
Iraqi military spokesman Brigadier Qassim Musawi said on March 13 that the number of people in the capital killed in the 30 days since Operation Enforcing the Law began was 265. He said that was down from 1,440 in the previous month.
But he said that attacks in surrounding provinces have increased, though he gave no figures.
Speaking on March 12, U.S. Vice President Dick Cheney said time will be needed for the security operation to succeed.
"In Iraq, our goal remains a democratic nation that upholds the rule of law, respects the rights of its people, provides them security, and is an ally in the war on terror," Cheney said. "But for this to happen, the elected government in Iraq needs the space and the time to work on reconciliation goals, and it's hard to do that without basic security in Baghdad."
Most recently, Washington has also begun exploring ways to improve the security situation in Iraq by talks with neighboring countries, including Iran and Syria. Washington charges both states with activities that help fuel the violence in Iraq.
Washington accuses Iran of funding and providing military expertise to militant Shi'ite groups and says Syria does too little to stop the flow of funds and foreign fighters to insurgent Sunni groups.
On March 6, Iraqi Prime Minister Nuri al-Maliki opened a first-of-its-kind conference including the United States, Iran, and Syria in Baghdad.
"We ask the participants, and through them the international community, to be aware of the historic and social specificity of Iraq," al-Maliki said in his opening address. "[We ask] that some countries or regional or international parties not to seek to have a quota or influence in Iraq through influencing a certain sect or ethnic community or a party."
It remains unclear where such regional diplomacy may lead. The participants agreed to meet again at the ministerial level soon -- likely in April -- but have yet to set the time and place.
One big question hanging for the year ahead is how open-ended the U.S. troop commitment will remain. The leadership of the opposition Democratic Party-controlled U.S. Congress is seeking support for a resolution to withdraw most U.S. combat troops in 2008.
The Bush administration rejects that idea, saying any timetable will encourage insurgent groups.
Britain has said it will withdraw some 3,000 of its total of 7,200 troops in southern Iraq in the coming months. London says the Shi'ite-majority south is now stable enough to allow it to do so.
In Iraq, the violence has caused large numbers of people -- from almost all communal groups -- to leave their homes.
The United Nations refugee agency estimates that some 1.7 million people -- or 12 percent of Iraqis -- have fled abroad, mostly to neighboring states. Hundreds of thousands more have moved inside the country to safer areas, often along communal lines.
Four years after the start of U.S.-led military operations, the question of when these Iraqis can ever return home remains without an answer.
The Imam Al-Mahdi Army on parade (epa)
HAS THE CONFLICT IN IRAQ BECOME A CIVIL WAR? Many observers have concluded that the tit-for-tat sectarian violence that emerged after the February 2006 bombing of a mosque in Samarra has become a full-blown civil war.... (more)
U.S. Media Starts Using 'Civil War' Label
Iraqi Prime Minister Under Fire From All Sides
U.S. Expert Discusses Prospects For Stabilization
President Says Iraq Needs Iran's Help
Saudi Arabia To Seal Off Border With Security Fence
THE COMPLETE PICTURE: Click on the image to view RFE/RL's complete coverage of events in Iraq and that country's ongoing transition.