The Syrian Democratic Forces (SDF), supported by a USA -led coalition, announced a final push to retake the militant pocket late Saturday, after a pause of more than a week to allow civilians to flee.
The SDF on Saturday launched a final push to clear the area from ISIL under the cover of airstrikes by the US -backed coalition.
A top USA general said last week ISIL would pose an enduring threat following the US withdrawal, as it still has leaders, fighters, facilitators and resources.
Before the assault began at sunset on Saturday, civilians could be seen fleeing the town.
Backed by coalition air strikes, the SDF alliance has been battling to oust the jihadists from the eastern province of Deir Ezzor since September.
France's Defence Minister Florence Parly visited the Iraqi side of the border on Saturday where France has a forward artillery base near al-Qaim, just a few kilometres from Baghouz.More news: PSG striker Cavani could miss Man Utd first leg
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It should be noted that Trump's latest rhetoric seems a preparation for quick pullout, or big coming announcement: "It should be formally announced sometime, probably next week, that we will have 100% of the caliphate", the president said Wednesday during an anti-ISIL coalition speech at the State Department.
"In conclusion, we are at the onset of a longer fight against ISIS which will require deep coordination, unity, and preparedness". They say ISIS still has enough leaders, fighters, facilitators and financial resources to fuel a menacing insurgency. On Monday, the chief spokesman told CBS News there were far more civilians trapped inside that village than previously thought.
The capture of the ISIL-held village and nearby areas would mark the end of a four-year global war to end ISIL's territorial hold over large parts of Syria and Iraq.
It is also unclear whether the United States will be able to satisfy the security concerns in Syria of its North Atlantic Treaty Organisation ally Turkey without sacrificing the interests of US -backed Kurdish fighters there.
A top USA commander has issued a warning saying there are "tens of thousands" of ISIS fighters spread across Syria and Iraq.
Analysts have warned the U.S. decision to pullout troops from Syria will leave a vacuum that will "increase the worldwide and regional conflict" for power and influence in Syria. "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. IS also is using civilians as human shields, the Observatory said.
With the end of combat operations in sight, the U.S. is just weeks away from withdrawing its troops from Syria, the top USA commander overseeing American forces in the Middle East said on Sunday. "The sticking point between us and the U.S.is [their] choice of allies".