The Islamic State, as demonstrated by its siege of Kobane under a relentless US aerial assault, is a tactical fighting force, capable of maintaining discipline even in the face of another determined force, the Kurdish YPG. And as the militant group continues its quest to expand the borders of its nascent caliphate, there appears to be an emergent, sophisticated military strategy that experts have now discerned.

It combines a diffuse leadership structure with a multi-pronged military strategy of terrorism, guerilla warfare and conventional warfare, according to the Institute for the Study of War. The last, however, is what makes the group unique in the annals of terrorist organisations: The Islamic State doesn't just operate as a military force - but a tactical one.

"One of the hallmarks of ISIS's military strategy has been to launch several attacks simultaneously, distracting opponents from its real target," the New Yorker's Dexter Filkins recently wrote, referring to one of the several names (including ISIL) used for the group. "The group is fighting on many fronts in Iraq and Syria, [Iraqi ISIS expert Hisham] Alhashimi said, and he believes that it may be planning a major attack somewhere else - in the Gulf or in Europe."

Its fighting style reflects those of previous militant groups. Writing in the respected Small Wars Journal, First Lieutenant Dennis Lowe said the Islamic State uses something called a "rule-based swarm manoeuvre system" that draws from Somali tactics in the early 1990s. What the strategy means in plain English: "Maintain an extended line abreast, keep your neighbours just in sight, but no closer, move to the sound of guns, dismount when you see the enemy, when you come under fire, stop and fire back."

David Kilcullen, the famed counterinsurgency expert who helped design the "surge" in Iraq, described how the Somalis used the "swarm" in his book, Out of the Mountains: The Coming of Age of the Urban Guerilla.

In an urban environment, where firefights tend to be fleeting and to occur at short ranges among small numbers of combatants, the terrorists' ability to operate in a distributed swarm of autonomous small teams, with low signature and high mobility was a key tactical advantage.

It's a perfect tactic, First Lieutenant Lowe said, for a diffuse military like the Islamic State. Though it's ostensibly led by Abu Bakr al-Baghdadi, many of his lieutenants and deputies act autonomously, and the control structure is very decentralised. And the "swarm" tactic "requires minimal command and control and is adaptable to almost any situation."

From Mosul to Sinjar to Kobane, the strategy re-emerged as the Islamic State has widened its territories. And in those targets lay more clues. Everything for the Islamic State hinges on controlling regional cities, which Lowe calls its "primary objective". Once inside a city, the group initiates the second part of what has been an equally successful campaign of occupation. The Islamic State has rarely lost a city once it has seized it.

Much has been made of the barbarity of life under Islamic State rule, and there's every indication that it's rough, marked by regular public executions. But there's a two-pronged method to it, according to Al Monitor. The first is to "openly intermingle with the local population, especially ISIS sympathisers or those predisposed to being sympathetic to ISIS, to push them to revolt against the government." And the second is to undermine the legitimacy of the city's ruling party and "weaken confidence in the government's security services".

And slowly the community is subjugated not just through force but through the power of ideology. Its "power is dependent on its control of populations and the flow of resources," Lowe wrote: "… A large, competent combined arms force is the only way to completely defeat [it] and drive it from urban strongholds."

Which makes its assault on Kobane all the more terrifying. If the city falls to the Islamic State, as the Turkish president fears, it may be hard to dislodge it.

Washington Post