The U.S.-led coalition against the Islamic State on Sunday congratulated the Government of Iraq on its announcement of the liberation of Iraq from ISIS.

“The Coalition congratulates the Government of Iraq on its announcement of the liberation of Iraq from Daesh,” a statement from the coalition said, using a derogatory Arabic term for the terrorist group.

“Much work remains, and we will continue to work by, with and through our Iraqi partners to ensure the enduring defeat of Daesh and prevent its ability to threaten civilization, regionally and globally,” said Army Lt. Gen. Paul E. Funk II, commander of Combined Joint Task Force—Operation Inherent Resolve (CJTF-OIR).

The announcement by the Iraqi government formally marked the end of a more than three-year occupation of major territory in Iraq by the terrorist group, which had subjugated Iraqi civilians to a life of brutality and violence in areas under its control.

“Honorable Iraqis: your land has been completely liberated. The dream of liberation is now a reality,” Iraqi Prime Minister Haider al-Abadi said in a televised address, according to Reuters.  “We have accomplished a very difficult mission. Our heroes have reached the final strongholds of Daesh and purified it. The Iraqi flag flies high today over all Iraqi lands.”

He declared December 10 a national holiday to be celebrated every year.

The terrorist group, in a lightning attack, swept into Mosul and other areas of Iraq in the summer of 2014, threatening the capital of Baghdad itself.

The Obama administration, which had withdrawn all U.S. forces in 2011, sent U.S. forces back to Iraq, beginning with a few hundred advisers. That presence grew to an officially-recognized number of 5,262, but actually included thousands more who were in Iraq on an unofficial, part-time basis.

The Obama administration also sent an official number of 503 U.S. troops into Syria, which obscured hundreds more on the ground on a part-time basis. There were also thousands more U.S. troops based across the border in Kuwait, and in the region.

President Trump campaigned on defeating ISIS, and earlier this year, granted Defense Secretary Jim Mattis and U.S. commanders in the field more authority to go after the terrorist group. Mattis implemented an “annihilation” strategy that aimed to surround and annihilate ISIS fighters, instead of an “attrition” strategy that was simply shifting ISIS fighters from one place to another in Iraq.

A coalition official at an undisclosed location in Southwest Asia told reporters from Breitbart News and other outlets visiting the region with Mattis last week that once coalition-backed Iraqi forces captured Mosul, ISIS’s morale collapsed.

“Once Mosul fell, they lost confidence,” the official said.

The U.S. military presence in Iraq and Syria is shifting from one supporting offensive operations against ISIS to stabilization—in other words, advising Iraqi forces on holding territory liberated from ISIS and returning life back to normal, according to defense officials.

There is no timeline for withdrawal for U.S. forces in either area, but the overall number of U.S. troops is expected to go down. The Pentagon said last week there are about 5,200 U.S. troops in Iraq and about 2,000 in Syria.