The Syrian Observatory for Human Rights said on Wednesday that Islamic State militants had executed nearly 700 prisoners in nearly two months in eastern Syria. The UK-based war monitoring group said the prisoners were among 1,350 civilians and fighters that Islamic State had been holding in territory near the Iraqi border.
The jihadists control a shrinking strip of land east of the Syria's Euphrates River around the town of Hajin, which U.S.-backed forces entered this month.
The Syrian Demoratic Forces (SDF), led by the Kurdish YPG militia, has battled Islamic State there for several months with the help of U.S. air power and special forces.
SDF commander-in-chief Mazloum Kobani said last week that at least 5,000 IS fighters remain holed up in the enclave, including many foreigners who appear ready to fight to the death.
Islamic State's self-proclaimed caliphate has crumbled after different offensives across Iraq and Syria, though its fighters still operate in the desert border region and mount attacks.
It comes as more than 200 mass graves containing the remains of thousands of people have been discovered in Iraq in areas formerly under the control of Islamic State (ISIS) militants according to the United Nations.
The UN firmly condemned the extremist group’s indiscriminate and widespread campaign of violence, which it says may amount to war crimes, crimes against humanity and genocide.
The bodies found inside the graves are believed to be the victims of the radical Sunni group, who between June and December 2014 seized large swathes of northern Iraq and declared it part of their so-called “caliphate”.
The victims include women, children, the elderly and disabled, as well as members of Iraq’s armed forces and police, a UN report said.
Today the United States said it is considering a total withdrawal of U.S. forces from Syria as it nears the end of its campaign to retake all of the territory once held by Islamic State, U.S. officials said.
Such a decision, if confirmed, would upend assumptions about a longer-term U.S. military presence in Syria, which U.S. Defense Secretary Jim Mattis and other senior U.S. officials had advocated to help ensure Islamic State cannot reemerge.
Still, President Donald Trump has previously expressed a strong desire to bring troops home from Syria when possible.
The timing of the withdrawal was not immediately clear and U.S. officials who spoke to Reuters on condition of anonymity did not disclose details about the deliberations, including who was involved. It was unclear how soon a decision could be announced.
The Pentagon and White House declined to comment.
The United States still has about 2,000 troops in Syria, many of them special operations forces working closely with an alliance of Kurdish and Arab militias known as the Syrian Democratic Forces, or SDF.
The partnership with the SDF over the past several years has led to the defeat of Islamic State in Syria but outraged NATO ally Turkey, which views Kurdish YPG forces in the alliance as an extension of a militant group fighting inside Turkey.
The deliberations on U.S. troops come as Ankara threatens a new offensive in Syria. To date, U.S. forces in Syria have been seen as a stabilizing factor in the country and have somewhat restrained Turkey's actions against the SDF.
A complete withdrawal of U.S. troops from Syria would still leave a sizeable U.S. military presence in the region, including about 5,200 troops across the border in Iraq.
Much of the U.S. campaign in Syria has been waged by warplanes flying out of Qatar and other locations in the Middle East.
Still, Mattis and U.S. State Department officials have long fretted about leaving Syria before a peace agreement can be reached to end that country's brutal civil war, which has killed hundreds of thousands of people and displaced around half of Syria's pre-war population of about 22 million.
In April, Mattis said: "We do not want to simply pull out before the diplomats have won the peace. You win the fight - and then you win the peace."
Islamic State is also widely expected to revert to guerilla tactics once it no longer holds territory.
A U.S. withdrawal could open Trump up to criticism if Islamic State reemerged.
Trump has previously lambasted his predecessor, Barack Obama, for the withdrawal of U.S. forces from Iraq that preceded an unraveling of the Iraqi armed forces. Iraqi forces collapsed in the face of Islamic State's advance into the country in 2014.