BEIRUT - A spokesman for Russian President Vladimir Putin says the unwillingness of the United States to work with Moscow in Syria has contributed to the loss of the ancient city of Palmyra to the Islamic State group.

Syrian troops aided by Russian airstrikes drove IS from Palmyra in March, but the militants stormed back into the city over the weekend.

Meanwhile, Syria's military says it has gained control of 98 percent of eastern Aleppo.