Yes they are Muslims and they are terrorists, but they also strongly self-identified as Chechens (bu looking at their past posts and pictures etc) so if this influenced their worldview, and if it might lead to any supporters, it is a lead that must be looked at objectively.
BS...Chechens and Sunni Muslims are the same thing. This area has been Muslim for 300 years. And they are chiefly Sunni...Don’t make excuses for them.