Cairo (CNN)As the assault to retake ISIS's last enclave of territory in Syria continues, the top US general overseeing the fight against the terror group warned Monday that if the terror group loses that fight it "doesn't mean the end of the organization."
"Liberation of the terrain that ISIS holds is important, it's an important objective for us to take that away from them. But it doesn't mean the end of the organization," Gen. Joseph Votel, the head US Central Command, told reporters on Monday while on an official visit to Cairo, Egypt.
"We are going to have to continue to put military pressure on them. The Syrian Democratic Forces will and we will help them," he added, referring to the US-backed group of Kurdish and Arab fighters that have been America's principal ally in Syria.
But Votel acknowledged that putting pressure on ISIS will be made more challenging without the presence of the over 2,000 US troops currently in Syria, forces that President Donald Trump has ordered to be withdrawn.
"Putting military pressure on is always better, it's always easier when you are there on the ground, but in this case our President has made a decision and we are going to execute that and so it's my responsibility as the CENTCOM commander working with my chain of command to look at how we do that," he added, saying that in 2014, the US managed to support Syrian Kurds fighting ISIS without US troops on the ground.
But while US military officials are planning for the next phase of the ISIS fight, including what to do about the thousands of dispersed fighters, Votel highlighted that the battle for the terror group's last redoubt in Syria will be a challenging one.
"It's a relatively confined space, it's heavily urbanized, it's laden with a lot of explosive hazards, improvised explosive devices for example, and kind of a prepared defense by ISIS. They have had the opportunity to prepare this for a while, and there is a presence of civilians in the area -- family members of ISIS and then others that reside in the area, so I think this poses a significant, a significant concern for us as we do this," Votel said.
He estimated that ISIS retained between 500 to 1,200 fighters in its last pocket of territorial control, which represents less than 1% of the territory the terror group controlled at its peak.
Many of those fighters are believed to be foreigners who traveled to Syria to join the terror group and have been unable to escape as they have been unable to blend in with the local population.
The detention of foreign fighters has been a point of concern among US officials who have expressed concerns about the fate of the detainees following Trump's decision to withdraw US troops.
While the Kurdish-led Syrian Democratic Forces have been able to operate detention facilities, there are concerns over what would become of the detainees being held there should Turkey attack the Kurds following a US withdrawal.
The US has made a concerted effort to have countries repatriate their citizens in detention in order to ease the burden on detention facilities but has had limited success in doing so.
Many countries are reluctant to do so because of the difficulty of prosecuting suspected ISIS members based on evidence collected on the battlefield.
"We need the nations where these fighters came from to take responsibility for their people and bring them back and get them into proper prosecution," Votel said
Votel added that the Syrian Democratic Forces "are holding over 800 foreign terrorist fighters from 50 different nations, so they are doing a service and they are doing a pretty good job of it within their capabilities, but what we do need is we need the international community to step up and take their people back and I think our government, all forms of the US government, have been very keen and very clear on this and very open to address this, but we do need them to take their fighters back."
CNN's Ryan Browne contributed to this report.