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A boy, displaced from fighting in the Islamic State stronghold of Raqqa walks in desert near village of Karama, east of Raqqa, Syria July 1, 2017. Goran Tomasevic/REUTERS

U.S. backed Syrian Democratic Forces (SDF) have nearly sealed off the remaining ISIS forces in Raqqa, Syria according to the New York Times Sunday. Raqqa has been the capital of the self-styled Islamic State since the extremist group declared their Caliphate, or reign, two years ago. The operation aims to trap and defeat a possible ISIS force of 2,500 militants. This push comes after a successful blow against ISIS on Thursday when Iraqi forces recaptured Al Nuri Grand Mosque in Mosul, an ISIS stronghold.

“We are seeing the end of the fake Daesh (ISIS) state, the liberation of Mosul proves that,” said Iraqi Prime Minister Haider al-Abadi on Twitter. “We will not relent. Our brave forces will bring victory.”

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Daesh is the Arabic acronym for ISIS.

If Syrian forces are successful in their fight, it would mark another huge blow to the physical presence of ISIS. The battle has been raging for a month and Reuters reported Sunday that SDF has deployed 1,000 additional troops for the fight. U.S. officials said that the city is nearly completely closed off except for one gap that remains near the Euphrates River that runs along the southern edge of Raqqa.

In addition to the ISIS militants, there are around 50,000 civilians left in the city, and officials fear that ISIS will use them as human shields.

A June U.N. report detailed how ISIS used human shields in Mosul and killed civilians as the tried to flee. Militants could use the same tactics in Raqqa.

“Shooting children as they try to run to safety with their families, there are no words of condemnation strong enough for such despicable acts,” said U.N. High Commissioner for Human Rights Zeid Ra’ad Al Hussein in a statement. “I call on the Iraqi authorities to ensure that those who are responsible for these horrors are held accountable and brought to justice in line with international human rights laws and standards. The victims of such terrible crimes must not be forgotten.”

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Complicating the final strike internationally are the tensions between Russia and the U.S. Russia is backing the Bashar al-Assad led Syrian government and their forces who are in opposition to the SDF in Syria’s ongoing civil war. Both sides are attempting to push ISIS out of the country. The American commander for the SDF and coalition forces fighting the ISIS militants is Lt. Gen. Stephen J. Townsend. His Russian counterpart Col. Gen. Sergei Surovikin leads the Syrian government forces and Iranian troops. The two leaders have agreed on a buffer that keeps their forces separated. The buffer also allows airstrikes to not interfere with each other.

Many of the leaders and administrators of ISIS have already fled to a town East of Raqqa called Mayadin.​