BAGHDAD -- Iraq's prime minister declared an end Saturday to the war against the Islamic State, more than three years after militants overran and captured one-third of the country and imposed a violent and austere rule over millions of Iraqis.
Iraqi and American officials warned, however, that key challenges remain despite the military victory.
Haider al-Abadi announced that the rugged, sparsely populated desert region bordering Syria has been "cleansed" of Islamic State fighters and that the porous border that had underpinned the self-declared caliphate that straddled both countries has been fully secured.
"This victory was achieved ... when Iraqis united to face a heinous enemy that didn't want us to see this day," al-Abadi said. "They wanted to return us back to the Dark Ages."
[THE ISLAMIC STATE: Timeline of group’s rise, fall; details on campaign to fight it]
Iraqi forces mopped up the last pockets of Islamic State fighters from Iraq's western deserts Saturday, securing the country's border with Syria, a step that marked the end of combat operations against the extremists.
"All Iraqi lands are liberated from terrorist Daesh gangs and our forces completely control the international Iraqi-Syrian border," said Lt. Gen. Abdul-Amir Rasheed Yar Allah, a senior Iraqi military commander, in a statement Saturday afternoon, using the Arabic name for the Islamic State, which is also often referred to by the acronym ISIS -- Islamic State of Iraq and Syria.
Saturday's declaration caps a war that has killed thousands of Iraqi troops in fierce battles for such cities as Tikrit, Ramadi and Beiji since 2015. But after losing the grueling nine-month battle for Mosul in July, Islamic State began to quickly collapse -- ceding its grip on smaller cities and towns in days rather than months.
The explosive rise of the militants in 2014 drew the United States back into Iraq, with more than 5,000 U.S. troops assisting Iraq's military as it wrested back land. The Islamic State's growth also saw the United States enter Syria's battlefields, already crowded with Russian and Iranian proxy forces buttressing the shaky rule of President Bashar al-Assad.
"The Coalition congratulate the people of Iraq on their significant victory against #Daesh. We stand by them as they set the conditions for a secure and prosperous #futureiraq," the U.S.-led coalition wrote in a tweet.
The U.S. applauded the prime minister's announcement.
The U.S. offers "sincere congratulations to the Iraqi people and to the brave Iraqi Security Forces, many of whom lost their lives heroically fighting ISIS," State Department spokesman Heather Nauert said in a written statement.
Brett McGurk, U.S. special presidential envoy to the anti-Islamic State coalition, posted a statement on his official Twitter account: "Our coalition will continue to stand with Iraq to support its security forces, economy and stabilization to help ensure that ISIS can never against threaten Iraq's people or use its territory as a haven. We mark today's historic victory mindful of the work that remains."
Last month, Iran and Russia declared victory over the Islamic State in Syria, though fighting continues in small pockets near the border with Iraq. The Syrian Democratic Forces, a group of mostly Kurdish fighters backed by the United States, won back the Islamic State's self-declared Syrian capital, Raqqa, in October.
Al-Abadi's comments came almost in passing as he attended a conference with the journalists union Saturday. The casual declaration of victory over the Islamic State came as the nation's attention has turned to a political standoff with Kurdish separatists and repairing the immense physical and social damage the militants left behind.
Later, in a 10-minute speech broadcast on national television, al-Abadi stood before columns of soldiers and police in front of the Defense Ministry and congratulated Iraqis on their victory. He highlighted national unity as the engine that powered the war against the Islamic State, telling Iraqis to "hold their heads high."
"Honorable Iraqis, your land has been completely liberated," he said. "The liberation dream has become a reality. We achieved victory in difficult circumstances and with God's help, the steadfastness of our people and the bravery of our heroic forces we prevailed.
"The flag of Iraq is flying high today over all Iraqi territory and at the farthest point on the border," he added, standing before the most senior members of Iraq's security forces.
After al-Abadi's remarks, his office declared a public holiday today in celebration of the victory, according to an official statement from the prime minister's office.
SOBERING TALLIES
Al-Abadi said the coming fight will be against rampant corruption, saying it is a natural extension of the war to use Iraq's resources for the benefit of the nation's citizens.
Although a large military parade to mark the victory is planned for the coming weeks, al-Abadi's announcement provoked little public jubilation, reflecting a mood in the country that is still grappling with its losses.
Iraq's government remains faced with significant security threats, an economic crisis and the task of rebuilding swaths of territory decimated by the Islamic State fight.
The Pentagon has acknowledged that at least 801 civilians have been mistakenly killed in U.S.-led airstrikes against Islamic State targets in Iraq and Syria. Airwars, an independent monitoring group, says the figure is likely much higher, totaling 5,961 since 2014.
Last week, an Iraqi official assigned to manage a fund to reconstruct cities such as Mosul said it would cost about $150 billion to rebuild these places -- the vast majority of which are in Iraq's Sunni heartland. About 3 million people remain displaced to this day.
In addition, 20,000 people accused of joining the Islamic State remain in detention, coursing through an overburdened criminal justice system that Human Rights Watch has said is unable or unwilling to provide fair trials and distinguish between those who eagerly killed for the group and those coerced into menial roles like cooks.
Iraqi forces are also bracing for the Islamic State's continued presence as an underground insurgency that has returned to its traditional tactics of terrorist attacks. Hours before al-Abadi spoke, a car bomb in Tikrit killed at least one person.
Islamic State insurgent networks continue to pose a threat to Baghdad and other Iraqi cities, a senior Iraqi security official said, speaking on condition of anonymity in line with regulations. The official said intelligence gathering would become increasingly important in the post-military phase of the fight against the Islamic State.
"The triumph of military operations alone is not enough without stability," government spokesman Saad al-Hadithi said, explaining that rebuilding in the wake of military victories against the Islamic State remained a "big challenge" for the Iraqi government.
Al-Abadi, who has won plaudits in Iraq for his posture of inclusion and efforts to reverse nearly a decade of his predecessor's sectarian policies that favored Shiites, has insisted that the conditions that gave rise to the Islamic State would return if there is no genuine nationwide move toward reconciliation.
"I urge everyone to refrain from returning to the inflammatory and sectarian discourse that empowered gangs to occupy our cities and villages," he said.
"Our people have paid a dear price," he added. "We must turn this page forever."
The appetite for such a reconciliation will be tested as campaigning for national elections set for May have begun. Powerful Shiite militias that played a significant role in freeing Sunni lands occupied by the Islamic State are expected to field dozens of candidates, some of whom are closely aligned with Iran and embrace a sharply sectarian narrative that pins the Islamic State's rise on widespread support by Iraq's Sunnis.
Al-Abadi has insisted that the militia figures who want to contest elections must disarm, a demand many Iraqis see as impossible to impose given how deeply enmeshed the militias are in Iraq's security apparatus. Badr Organization, one of the oldest and largest Iran-backed Shiite militias in Iraq, already controls the Interior Ministry and holds 22 seats in parliament.
In his speech on Saturday, al-Abadi hinted at this looming challenge.
"The only way to build a state and achieve justice and stability, is by keeping arms under the control of the state and the rule of law," he said.
Information for this article was contributed by Tamer El-Ghobashy and Mustafa Salim of The Washington Post; and by Qassim Abdul-zahra, Susannah George and Sinan Salaheddin of The Associated Press.
A Section on 12/10/2017