In northern Syria, an air strike has killed at least 25 members of a prominent militant group. UK-based Syrian Observatory for Human Rights said, it is not clear who carried out the attack against the Jabhat Fateh al-Sham group, formerly known as Nusra Front. The Observatory said, an unidentified aircraft hit one of the group's most important bases in Syria, in the northwestern province of Idlib. <br/><br/>The strike came days after a ceasefire between Syria's regime and major rebel groups brokered by Russia and Turkey. Meanwhile, rebel groups say they are halting the preparations for peace talks. A statement signed by a number of groups cited many big breaches by the Syrian government and its allies as a reason.'The ceasefire was brokered last Thursday and has mostly held since then. Peace talks were planned for later this month in Astana, Kazakhstan.