The besieged Syrian city of Aleppo was hit with at least four airstrikes on Sunday despite a ceasefire agreement, according to the Syrian Observatory for Human Rights. The strikes hit rebel-held areas of the city, which has been a hotbed for violence in the country’s civil war in recent months. French Foreign Minister Jean-Marc Ayrault blamed Bashar al-Assad’s government for the majority of airstrikes since the ceasefire was agreed to by the U.S. and Russia last week. The ceasefire does not include offensives against ISIS or other Islamic militant groups. On Saturday, the U.S. took responsibility for airstrikes that killed more than 60 Syrian troops. In a statement released shortly after those attacks, Russia accused the U.S. of borderline collusion with ISIS fighters.