Thousands of suspected ISIS fighters have attempted to blend in with civilians fleeing the militant group's battered last bastion, including a large number of foreigners.
The Baghouz area on the shores of the Euphrates River in eastern Deir ez-Zor province, near the border with Iraq, is the last piece of significant territory held by the jihadists who had once controlled swathes of land across Iraq and Syria.
He later wrote on Twitter that the battle had started and the enclave would "be cleared soon".
An official from the Syrian Democratic Forces, the US-backed alliance which is spearheaded by the YPG, told Reuters: "What we know is that so far there is no withdrawal, and the situation on the ground is unchanged".
"We have chosen a political agreement with Damascus because we don't want secession from Syria".
He said: "It should be formally announced sometime, probably next week, that we will have 100 percent of the caliphate".
"Remnants - that's all they have, remnants - but remnants can be very risky", Mr Trump said.More news: Trump drags Schiff again in morning Twitter screed
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His words were echoed Friday by France's defence minister during a visit to neighbouring Iraq.
On Thursday, the coalition said the "caliphate" had massively shrunk.
Trump made the statement during his speech to the Global Coalition to Defeat ISIS on Wednesday at the U.S. State Department, . praising the territorial gains made against the terror group. While the bounty doesn't explicitly reveal the reason why the veteran foreign terrorist fighter has fallen in disfavour, intelligence officials, cited by The Guardian, suggest that he led the unsuccessful coup attempt aimed against the leader, Sputnk says.
Bali said there could be up to 600 ISIS fighters still inside the pocket, majority foreigners.
According to the Observatory, more than 37,000 civilians, including dozens of IS militants, have fled the last IS-held pocket to areas controlled by the SDF in the eastern Euphrates region since last December.
The Britain-based Syrian Observatory for Human Rights, a war monitor, said SDF fighters are advancing "cautiously" due to mines planted by IS gunmen.
But Kurdish officials told AFP on Friday there had been no progress on reaching a deal with Paris.