Reuters reports: Bashar al-Assad’s former defense minister has reached Istanbul after a defection that betrays cracks in the president’s support among his own Alawite sect, opposition and diplomatic sources said on Thursday.

Dismissing a cursory Syrian state television denial of the first Reuters report that General Ali Habib had been spirited across the Turkish frontier this week, opposition figures said Habib was likely to keep a low profile after evading house arrest and reaching Turkey with the aid of Western agents.

One prominent opposition figure also spoke of speculation that Habib, who is in his 70s and apparently broke with Assad after a crackdown on protesters in 2011, might be lined up by U.S. and Russian officials for a role in transitional arrangements to negotiate an end to the civil war.

“My information, based on a trusted Western source, is that he is in Istanbul,” veteran dissident Kamal al-Labwani, now based in Paris, told Reuters on Thursday. “Habib exited with Western intelligence involvement, so do not expect public statements by security operatives on his whereabouts.”