(CNN)As US-backed forces tighten their grip on ISIS's Syrian capital Raqqa, and Iraqis celebrate the liberation of Mosul, the man tasked by both the Obama and Trump administrations to coordinate the anti-ISIS effort sees reason for optimism.
Top US official: ISIS is shrinking but "end stage" is some way off
In a wide-ranging interview with CNN this week, Special Presidential Envoy for the Global Coalition to Counter ISIS Brett McGurk hailed the coalition's progress against the terror group -- which spread through Iraq and Syria at a lightning pace three years ago.
"We've retaken about 70,000 square kilometers," he said. "Five million people, Iraqis and Syrians, who were living under ISIS, have now been freed. And really, most importantly, the migrant refugee flow that we used to see has now reversed."
McGurk, who was appointed to the special envoy position by former President Barack Obama, credits President Donald Trump for accelerating the pace of the effort by delegating more tactical decision-making authority to military commanders on the ground in Iraq and Syria.
"That has allowed us to really take advantage of some opportunities that we saw developing, particularly on the ground in Syria," he said, specifically citing an offensive in May to retake the town of Tabqa, and surrounding areas, which McGurk says helped "tighten the noose around Raqqa."
It's a shift welcomed by Defense Secretary James Mattis as well. In May, he told reporters, "no longer will we have slowed decision cycles because Washington DC has to authorize tactical movements on the ground."
The Obama administration had been widely criticized by world leaders and US lawmakers, for not taking a more decisive approach against the terror group, which seized broad swaths of territory in western Iraq in the summer of 2014 before declaring itself a "Caliphate."
But Obama stuck to his more cautious approach, telling reporters in 2015 he would "continue to pursue the strategy that has the best chance of working, even though it does not offer the satisfaction ... of a neat headline or an immediate resolution."
McGurk, for his part, stopped short of disparaging the former President's strategy, but acknowledged "there was much more of a deliberative process for certain things" before Trump was sworn in.
Tony Blinken, a CNN Global Affairs Analyst who served as Deputy Secretary of State under Obama, argued that the Trump administration can't take full credit for the success of the anti-ISIS effort over the past few months.
"All the gains are the culmination of the comprehensive strategy Obama put in place and implemented including the liberation of Mosul and soon Raqqa," he said. "(The Trump administration) have done virtually nothing different."
An especially important gain for US officials is the sharp decline in the number of foreign fighters entering Iraq and Syria to join ISIS, down about 90% from ISIS's peak in 2015, according to McGurk.
These fighters, which include some Americans, have troubled world leaders since the ISIS Caliphat9e was declared in 2014, because of the threat they could pose to their homelands if they're able to return.
"We do not want foreign fighters to escape (Iraq and Syria)," McGurk emphasized. "The foreign fighters are the suicide bombers; the foreign fighters are the terrorists who are trying to terrorize our homelands."
"We want to make sure that any foreign fighter that gets in to Syria or Iraq will die in Syria and Iraq," he continued. "We do not want these people to get out, and so far I think now the record is pretty good."
But as the coalition began to shut off ISIS's corridors in Iraq and Syria, its supporters increasingly began flocking to affiliates in other countries, Libya in particular.
"Libya was the place and now it's really inhospitable to them," said McGurk.
So where are these fighters flocking now?
"Some of them are trying to get to the Philippines," said McGurk, "and we're working very closely with our partners in that part of the world -- Australia, Malaysia, Indonesia and the Philippines."
While McGurk was cautious not to declare an "end stage" in the fight against the terror group, he said the offensive on Raqqa has effectively crippled the group's ability to dispatch resources, and -- perhaps more importantly -- to plan external attacks, like those launched in Paris in 2015, and Brussels in 2016.
"They were hanging out in civilian apartment buildings, high-rise apartment buildings, planning and plotting major attacks against the United States," he said of ISIS leaders, "And they were doing that only a few months ago."
"And they can really no longer do that," he said.
"As they lose territory they want to try to prove their relevance and legitimacy," he acknowledged. "So they are still trying to inspire (attacks)."
"But again," McGurk continued, "when they have a major infrastructure of a city, when they have Internet access, when they have phones that are connected to the outside world, that's much different than when they're in very small towns in which we're doing everything we possibly can to make sure they can communicate and that they are first and foremost focused on their own survival day-to-day."
And what of Abu Bakr al-Baghdadi, ISIS's reclusive leader, who Russian authorities say they may have killed in an airstrike in May?
"We assume that he's alive," said McGurk. "But his command and control over his forces have basically been severed."
"If he's in Raqqa, he's going to die soon, because anyone, any fighter left in Raqqa is going to meet that fate," he went on. "We assume that he would have slipped out of Raqqa and he's in one of these small towns, in hiding."
While the US military and its partners are making inroads, there's growing concern about the humanitarian situation in areas liberated by ISIS.
Urban warfare in Mosul and Raqqa has displaced hundreds of thousands of civilians, and leveled city blocks.
But the Trump administration's civilian footprint in northern Syria specifically has been limited to small "stabilization units," comprised of a handful of State Department personnel, who coordinate with local authorities and nonprofits to clear landmines and rubble, and bring in vital infrastructure.
"That's where we stop," Tillerson told reporters at a recent press conference. "We get the essentials in place."
"We're not there to rebuild their communities," he added. "That's for them to do and that's for the international community to marshal the resources to allow them to do that."
And as the Trump administration touts the success of its efforts against ISIS, achieving a resolution to the broader conflict in Syria has proven more elusive.
While the United States insists that Syrian President Bashar al-Assad must go in the course of a United Nations-backed political process, McGurk acknowledges, "it might take a period of some years to get to that outcome."