The father is living in the capital of Dagestan which is still in conflict with Russia. The boys grew up in Chechnya which was at war with Russia, but now ruled by a former rebel who now supports Putin and vice versa. I believe one or both boys visited that area in recent years. These facts present opportunity for all sorts of speculation, plus statements here at FR on another recent post that at least one son was a Mahdist believer, which may be even more important.