After Raqqa's liberation, 'a tough fight still lies ahead' against ISIS

— -- The liberation of Raqqa on Friday marked a historic end to the physical caliphate declared by ISIS in June of 2014.

Syrian Democratic Forces, who fought for months to reclaim the city, celebrated in Naim Square this week -- driving trucks and waving flags in the same place where ISIS had once beheaded its opponents. It was in Raqqa where ISIS fighters planned devastating attacks in Paris, Brussels, Nice, Manchester and beyond.

Despite the military's victory, there is still much to be done in Raqqa, from securing the city and restoring essential services to combating the last pockets of ISIS in eastern Syria and western Iraq. More broadly, the group's global network of finance, recruitment, and plots must be dismantled.

"The military defeat of Daesh is essential, but not sufficient," said U.S. Coalition Commander Lt. Gen. Paul E. Funk II, referring to ISIS by its Arabic acronym. "We are still fighting the remnants of Daesh in Iraq and Syria, and will continue to facilitate humanitarian efforts assisting citizens adversely affected by a brutal occupation, who face a long battle to gain their freedom. A tough fight still lies ahead."

ABC News breaks down what is next in the fight against ISIS following Raqqa's liberation.

Returning life to Raqqa

While the victory may have been declared on the battlefield in Raqqa, the field itself is still riddled with unexploded bombs, booby-trapped improvised explosive devices, and other hazards. The first task is to make the place safe for life to return -- a multi-step process that begins with de-mining.

The U.S. has an expert team of civilians deployed from the U.S. Agency for International Development (USAID), and they are working with partner NGOs to remove those weapons. Many of those devices have been placed by ISIS in homes and other buildings to kill as many returning civilians as possible. At one water treatment facility north of Raqqa, teams found approximately 240 explosive devices left behind, according to U.S. Special Envoy to the Global Coalition Brett McGurk.

After de-mining, rubble must be removed to clear the streets so that aid trucks can roll in, and utility services such as running water and electricity must be restored for the residents who come back. While this whole process has started -- and been underway in the areas outside Raqqa's center already -- it will take time.

"It'll be months if not longer before Raqqa is safe for residents to return home and before life as normal can eventually resume," State Department Spokesperson Heather Nauert told reporters Thursday, although she noted there is a "template" for rebuilding that has been used in nearby liberated cities like Taqba.

In the interim, the U.S. is helping to deliver aid to the internally displaced people who have fled ISIS, the Assad regime, and the brutal fighting of the six-and-a-half-year civil war. United Nations groups have delivered food aid to more than 260,000 people in the Raqqa area, with food stocks capable of feeding more than 50,000 people for one month, according to Nauert.

Who's in charge?

One of the most difficult questions for the U.S. and its allies to answer is with ISIS out, who takes over? A legitimate and fair governing body is needed to secure the military's gains and prevent the same conditions that spawned ISIS's rise. It's also crucial that such a body supports local people and their needs.

The problem is that the Raqqa area is predominantly Arab, but the Syrian Democratic Forces that liberated the area with U.S. support have a large Kurdish contingent. While they are among the region's strongest fighting forces, they could potentially be seen by locals as an occupying power.

The Trump administration is loath to step in after declaring an end to the kind of American "nation-building" that was done throughout the wars in Iraq and Afghanistan. "As a coalition, we are not in the business of nation-building or reconstruction," Secretary of State Rex Tillerson told a summit of the Global Coalition to Defeat ISIS in March.

Instead, the U.S. is supporting a governing body of local officials known as the Raqqa Civilian Council, which was formed in May with around 100 Syrians from different ethnic groups who are all native to the area. By their own decree, they will rule until May 2018, when there will either be an election for a new council or some other group established.

"Whoever eventually would run local governments should be representative of the people, should embody and believe in fundamental human rights and protection of those civilians in the area," Nauert repeated Thursday.

"This is, like, the most difficult, complex thing imaginable, so this will be extraordinarily hard," McGurk told reporters in September, promising that "areas that are retaken from ISIS, they will be controlled by the local people who know the areas, pending a longer-term political settlement to the civil war."

But the threat is that the brutal regime of Bashar al-Assad and its allies are trying to create a settlement on their terms through a bloody win on the battlefield. The Lebanese Shiite group Hezbollah, armed and supported by Iran, declared, "We have won in the war" in September. Russia's military has said Assad's forces had control of 85 percent of the country -- a claim quickly dismissed by several observer groups.

While those actors push for the return of Assad's control, the Trump administration maintains that Assad has no future in Syria.

"We’ve made clear many times that we do not believe at the end of this process that Assad should remain, that he has lost his legitimacy and his right to rule," the U.S.'s top diplomat in the Middle East, David Satterfield, said September 18. "But that is a decision for the Syrian people to make."

The Trump administration has also set a new requirement on reconstruction efforts meant to keep Assad from consolidating power, vowing to withhold international funds from the U.S. and the Global Coalition if Assad were to return to power. But it's unclear whether that is enough leverage, given the support that Assad enjoys from stalwart allies like Russia and Iran.

Chasing ISIS in the Euphrates River Valley

As the SDF made progress in the fight for Raqqa, ISIS leadership, including their media operations and administrative bureaucracy, fled south into the middle Euphrates River Valley, an area in eastern Syria that will be "the final stand of ISIS," Lt. Gen. Stephen Townsend, the former commander of the coalition, predicted in August.

Most, if not all, "high-value targets" struck by the coalition this year have been in that area, and airstrikes continue in the region in border cities like Al Mayadin and Abu Kamal.

But, for now, all eyes are on the Syrian city of Deir ez Zor, where Russian-backed Syrian regime forces and their Iranian-backed allies are waging their own battle against ISIS -- creating a delicate tightrope for the U.S.-backed rebels to walk.

On September 9, the SDF announced that they were shifting forces north of that city to conduct Operation Jazeera Storm against ISIS in the Khabur River valley. But that campaign has proven particularly challenging due to the battle space's proximity to the Syrian forces in Deir ez Zor.

One week after the new operations began, a Russian airstrike hit and wounded several SDF. No U.S. troops, who were part of the coalition forces embedded with the SDF at the time, were injured, but the incident triggered the "highest levels" of Pentagon and State Department officials to communicate with their Russian counterparts.

In the days after, U.S. and Russian general officers met face to face for the first time to "adjust and expand deconfliction measures," Col. Ryan Dillon, spokesman for the coalition, told reporters. A second meeting was held in mid-October.

But as the battle space continues to shrink, it seems inevitable that the two sides will collide again as they close in on ISIS.

Challenging ISIS around the world

Even after the last pockets of ISIS are cleared in Iraq and Syria, the fight against the extremist group remains a global challenge.

ISIS has affiliated organizations in Africa, Yemen, the Philippines, Afghanistan, Libya, Bangladesh, and beyond. Those groups perpetrate attacks almost constantly.

In Niger, an attack on a patrol of U.S. and Nigerien forces killed four U.S. soldiers and wounded two others. The Oct. 4 attack once again highlighted ISIS's presence in West Africa.

In other countries, like Afghanistan, the fight against ISIS groups is more well-known. The U.S. has increased its troop presence in Afghanistan by about 3,000 to align with the Trump administration's new "South Asia Strategy" and combat ISIS and the Taliban there.

Even in places without formal ISIS-affiliated groups, ISIS can promote their ideology online and inspire individuals around the globe to commit one-off attacks like those seen in San Bernardino and Orlando in the United States. Senior Pentagon officials refer to this as ISIS's "virtual caliphate," which they have said can only be countered in cyberspace.

But while the physical caliphate collapses, a virtual caliphate could prove impossible to completely eradicate.