Ibn al-Khattab
According to Fawaz Gerges who cited Abu Walid al Masri's diaries, Ibn al-Khattab and Osama bin Laden operated separate groups, as they defined the enemy differently, but tried to pull each other to their own battle plans. A part of bin Laden's interest was trying to obtain weapons of mass destruction (or at least dirty bombs) from the Russian arsenal through al-Khattab's contacts.