U.S. officials have concluded that Russia had advance knowledge of a chemical weapons attack against Syrian civilians last week, the Associated Press reported Monday. The official, who spoke under the condition of anonymity, said Russia flew a drone over a Syrian hospital where people were seeking treatment in the immediate aftermath of the chemical attack. Hours later, a Russian-made fighter jet bombed the hospital, the official said. U.S. intelligence was previously unsure whether the jet was Russian or Syrian. While the official said it is still unclear who was operating the jet, U.S. intelligence now believes the bombing to have been a Russian strike intended to cover up the signs of the earlier chemical weapons attack, indicating that Russia had advance warning of the chemical attack. The Kremlin currently maintains that it is unclear whether the Assad government was behind the chemical attack.