Is This the Beginning of the End for ISIS?

Members of Iraqi Federal police carry suicide belts used by Islamic State militants in the Old City of Mosul, Iraq July 9, 2017. Alaa Al-Marjani/Reuters

The Iraqi army, in conjunction with the U.S.-led coalition, has pried the northern city of Mosul from the Islamic State group's (ISIS) brutal grasp three years after the militant group's leader, Abu Bakr al-Baghdadi, first declared a caliphate inside a renowned city mosque.

Iraq's Prime Minister Haider al-Abadi arrived in Mosul Sunday to officially mark the city's liberation, congratulating "the heroic fighters and the Iraqi people on the achievement of the major victory," his office said in a statement.

But what happens now?

And what were the costs of the campaign?

Many neighborhoods in Iraq's second largest city are reduced to rubble, where ISIS militants' bodies are left to rot in the sun. Two-and-a-half weeks ago, the militant group blew up the 842-year-old Great Mosque of al-Nuri where Baghdadi announced the caliphate.

The nine month-battle to recapture Mosul was one of the bloodiest in the fight against the militant group. Iraq's premier fighting force, the Counter Terrorism Service (CTS), suffered 40 percent battle losses in the city and thousands of civilians died as well.

Now the Iraqi army is requesting more funding from the U.S. government to continue the pushback and ensure ISIS fighters don't return.

Read more: ISIS nears U.S. military base in Iraq, slaughters journalists

The group still has a stronghold in the city of Raqqa, Syria. A month into a campaign to capture the city U.S-backed Syrian forces have barely begun the fight into the heart of the city. Some 2,000 militants and their families have fortified themselves in the densely populated center, among tens of thousands of civilians.

Whereas Mosul was a yearlong campaign, "I don't think Raqqa will take that long, but it will take time," U.S. special envoy Brett McGurk told the Dubai-based Al-Aan TV last month during a visit to the frontline.

The group's ability to inspire attacks in other parts of the world hasn't stopped with the loss of Mosul. Jihadi groups in Indonesia and Nigeria have also claimed allegiance with the group.

"ISIS today is an international organization," Hassan Hassan, a senior fellow at the Tahrir Institute for Middle East Policy in Washington told The New York Times Saturday. "Its leadership and its ability to grow back are still there."

But there is more positive news: ISIS' revenue—which was helping to fund its reign of terror that started with the capture of cities, villages and territory across Iraq and Syria in 2013— dropped 80 percent in the past two years, according to a report released late last month by IHS Markit, as the group lost oil and taxes from the territory it previously held.

The loss of Mosul and the siege of Raqqa "are major blows to ISIS because its state-building project is over, there is no more caliphate, and that will diminish support and recruits," Hassan said.