Al Jazeera
At least 28 civilians have been killed and dozens wounded in air strikes by the US-led coalition in Syria, amid setbacks to attempts by the US to partner with Russia against the Islamic State of Iraq and the Levant (ISIL) group.
Thursday's air strikes hit the ISIL-controlled town of Ghandour, according to the Syrian Observatory for Human Rights (SOHR), the Britain-based organization.
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The town lies 23km northwest of Manbij, a strategic waypoint between Turkey and the city of Raqqa, the de facto capital for ISIL, also known as ISIS.
The US military acknowledged on Thursday that there may have been civilian deaths.
US Central Command, which oversees US military operations in the Middle East, said it had "initiated an assessment following internal operational reporting that a strike today near Manbij, Syria may have resulted in civilian casualties".
The strikes came a day after the coalition opened a formal investigation to determine whether its air strikes last week near Manbij claimed civilian lives.
The SOHR and local residents said the air strikes on July 19 had killed dozens of civilians, including children.
After examining "internal and external information", the coalition determined that there was sufficient credible evidence of civilian victims to open a formal inquiry, spokesman Colonel Chris Garver said on Wednesday.
Garver said last week that ISIL had been mounting exceptionally fierce resistance in Manbij, which is being besieged by US-backed Syrian forces.
New obstacles
According to the SOHR, around 600 Syrians, including 136 children, have been killed in coalition air strikes since September 2014.
Reports of further civilian deaths from coaltion air strikes come as attempts by attempts by John Kerry, the US secretary of state, to elicit Russian cooperation in the fight against ISIL hit two serious hurdles.
First, the Syrian army said it had cut off all supply routes into the eastern part of the city of Aleppo - Syria's most important opposition stronghold - and President Bashar al-Assad's government asked residents to leave the city.
That move, US officials speaking to Reuters news agency on condition of anonymity said on Thursday, appeared to be an effort to pre-empt the US demand that Russia and Syria reopen Castello Road before talks could begin on creating a joint intelligence centre to coordinate air attacks against ISIL.
Aleppo's Castello Road is a major channel into the divided northern city.
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Then al-Qaeda's Syrian branch announced on Thursday it was terminating its relationship with the global network created by Osama bin Laden and changing its name to remove what it called a pretext by the US and other countries to attack Syrians.
"We declare the complete cancellation of all operations under the name of Jabhat al-Nusra, and the formation of a new group operating under the name Jabhat Fath al-Sham, noting that this new organisation has no affiliation to any external entity," the group's leader Abu Mohammed al-Jolani said in an exclusive video obtained by Al Jazeera.
Although one US official called it "a change in name only", the move complicates the American proposal to limit the Russians and Syrians to targeting only al-Nusra and ISIL.
"By disavowing its ties to al-Qaeda - which, incidentally, it did with al-Qaeda's blessing - Nusra has made it harder to isolate it from more moderate groups, some of whose members may join it now because it's more powerful than some of the groups they belong to now," said the official.
Competing objectives
The two US goals in Syria have been ending the violence that has already claimed up to 400,000 lives, according to UN estimates, and seeking a political process to replace Assad, who President Barack Obama has said "must go".
But while the US and Russia have both expressed hope they can find a way to cooperate against ISIL, Kerry's proposal was already in trouble owing to the two powers' competing objectives as well as resistance from US military and intelligence officials.
US officials questioned Russian and Syrian claims that their aim in evacuating civilians from Aleppo was to clear the way for humanitarian assistance to reach the besieged city, where at least 300,000 civilians remain with only two to three weeks of food on hand.
"Why would you evacuate a city that you wanted to send humanitarian aid to?" one anonymous US official asked Reuters.
"At first glance, that would appear to be a unilateral effort by Moscow and Assad to pre-empt Kerry's demand for ending the siege of Aleppo before starting negotiations on the larger issues. If the proposal isn't dead, it seems to be pretty badly wounded."