The HV's success was a result of a series of improvements to the HV itself and crucial breakthroughs made in the ARSK positions that were subsequently exploited by the HV and the ARBiH. The attack was not immediately successful everywhere, but the seizing of key positions led to the collapse of the ARSK command structure and overall defensive capability. The HV's capture of Bosansko Grahovo just before Operation Storm and the special police's advance to Gračac made Knin nearly impossible to defend. In Lika, two Guards brigades rapidly cut the ARSK-held area lacking tactical depth or mobile reserve forces, isolating pockets of resistance and placing the 1st Guards Brigade in a position that allowed it to move north into the Karlovac Corps AOR, pushing ARSK forces towards Banovina. The defeat of the ARSK at Glina and Petrinja, after heavy fighting, also defeated the ARSK Banija Corps, as its reserve became immobilized by the ARBiH. The ARSK force was capable of containing or substantially holding assaults by regular HV brigades and the Home Guard, but attacks by the Guards brigades and the special police proved to be decisive. Colonel Andrew Leslie, commanding the UNCRO in the Knin area, assessed Operation Storm as a textbook operation that would have "scored an A-plus" by NATO standards.