BEIRUT (Reuters) - The U.S.-backed Syrian Democratic Forces (SDF), a leading combatant against Islamic State, on Thursday accused Turkey of pressuring one of its senior commanders into defecting.   Rebel officials said on Wednesday Brigadier General Talal Silo had defected, without giving a reason. It would be the first such departure from the SDF s top ranks. There was no comment from Turkey, which backs Syrian rebel factions and views the SDF, spearheaded by the Kurdish YPG militia, as a security threat.  Silo served as a spokesman for the SDF, an alliance of mostly Kurdish and Arab militias battling Islamic State in Syria with the help of the U.S.-led coalition. The SDF said in a statement they had  lost contact  with Silo, who had resigned from his post.   General Talal Silo was respected and appreciated among our ranks,  it said.  He was subjected to a lot of pressure and extortion from the side of the Turkish state, that amounted at some points to threatening his sons who are in Turkey.   We believe his disappearance is the result of a special operation by Turkish intelligence in collusion with some of his family members.   Kurdish fighters, alongside Arab allies, U.S. advisers and coalition air strikes, have driven Islamic State from swathes of territory including its former headquarters in Raqqa city. The YPG and its allies have carved out autonomous cantons in the north, and now control nearly a quarter of Syria. Their influence angers neighboring Turkey, which considers the YPG an extension of the banned Kurdistan Workers  Party, which has fought a decades-long insurgency on Turkish soil. The U.S.-led coalition had said it was  aware of reports of Talal Silo s apparent departure from the SDF, but have no further details on his current status at this time .  Our forces will not be affected by this incident, and we will inform the public of the results of our investigation,  the SDF said on Thursday.  
U.S.-backed Syria forces say Turkey pressured commander into defecting