There's been an element of islamism in the area for a long, long time. Probably due to the fact that chechnya is less than 300 miles north of both iran & iraq.
1999 January/February - Maskhadov declares Islamic Shari'ah law will be phased in over three years.
It is widely acknowledged that al-qaeda is fully operational in the caucasus region. The fact that the population of chechnya is majority muslim is a convenient excuse for terrorist extremists to exploit the situation and attempt to carry out their agenda. It is effectively a religious war going on between russia & chechnya.