Over the past two years, military operations in Iraq and Syria have shown the Islamic State to be an effective and lethal offensive war machine. In Al-Monitor in October 2014, I stressed that the effectiveness of IS' tactical offensive capabilities was due to its preservation of operational momentum at all costs and at every level. With Russia’s military intervention and high-paced operations with the Syrian army, the current issue is whether this situation might be changing. International news is laden with optimistic reports and forecasts that IS' offensives are losing momentum, that the tactical military scene is one of stalemate and that with the much-anticipated siege of Raqqa, the end of IS could actually be near.

Many military analysts, however, are warning against underestimating IS' defensive capacity. In “The Islamic State Digs In,” Jessica Lewis McFate does so by examining the situation in Mosul this year. According to McFate, Russian military intervention in Syria and its intention to expand its theater of operations toward Iraq might end up strengthening IS.

Can Kasapoglu, a security analyst with the Istanbul-based Center for Economic and Foreign Policy Studies, also believes the defensive potential of IS should not be overlooked. He told Al-Monitor, “First of all, I don't see [IS] as the primary objective of the current Russian-backed Syrian offensive. Nevertheless, in such a case, we would have to monitor the terrorist group's key tactical hybrid capabilities that could render the regime's as well as the Russians' armor and close-air-support superiorities ineffective. Put simply, given [IS'] advanced military planning, I don't see them maneuvering captured tanks and armored vehicles in open terrain when facing Russian Su-25 aircraft and Hind gunships.” 

In short, IS would probably depend on advanced, shoulder-fired anti-aircraft missiles and anti-tank guided missiles, which it has demonstrated it can use proficiently. Its unpredictable methods, especially suicide bombings, could be effective in striking key lines of communication and the rear areas of any offensive launched against it.