It would appear the Islamic State (IS) has set its sights on the United States. But still, the Obama administration remains shrouded in denial about the roots of radical Islamism.Unfortunately, the contemporary intellectual climate has blinded policymakers to the reality that the marauding Sunni militia is but the latest chapter in a longer saga of cataclysmic violence – uniquely Islamic.Those seeking to understand IS’s beastliness need to look no further than the Koran – which provides emphasis, symbolism and the process of law to IS’s proceedings. Yet it is precisely this kind of religious paradigm that policymakers, by no means lacking in enthusiasm, have roundly refused to consider.From an Islamist perspective, waging war to end the sovereignty and supremacy of the unbelievers is ultimately necessary and just. Far from abjuring violence, the Koran mandates religious wrath, jihad, as noble sentiment. Drawing swords is not religious fanaticism; it is, rather, a mode of faith believed to hasten the demise of infidels.The Islamic term for terrorism – in modern Arabic, irhab – connotes a form of religious struggle in which God’s vicegerents are the real believers, whose duty is to pursue justice through sanctioned violence.The Assassins, an ancient branch of Shi’ite Islam, were the first group to effectively employ systemic murder as a means of gaining political influence.They infiltrated the political circles of their intended victims, much the way IS is assimilating mischief makers into the swell of migrants and refugees turning up around Europe. With the passage of time, the instruments of Islamic warfare have changed – the Assassins carried sabers on horseback; today, IS fighters mount machine guns on Toyotas – but the overall objective remains fundamentally the same: to orient religion toward Allah.Unfortunately, reality reflects tradition. The infidels of yesterday – prophet-murderers, prophecy-deniers and the ongoing continuum of conspirators – are seen as the scoundrels of today. They are the collective affront that is Western civilization, targeted for extinction by radical Islam.Portraying the agents of this ancient ideological struggle as possessors of a tarnished truth – “a perversion of Islam” – is to ignore Islamic core texts, as well as significant experience.It is against this backdrop – unvarnished, without political correctness – that policymakers should confront IS.In the Middle East, wars are won with military hardware, not finely wrought political theories. Brutality – the “strong horse” principle – not lofty ideals about freedom, is the predominant governing philosophy of Middle Eastern culture.The Assassins were decisively defeated only when the cavalcading army of the Mongols, led by Genghis Khan, swept through Central Asia and annihilated them.The same principle must be applied to reshape the fight against IS. Rapid and overwhelming destruction and defeat is necessary to liquidate IS’s capacity to effectively govern, as well as to prevent it from recruiting more foreign fighters from around the world, some of whom are intent on returning home – bloodied, indoctrinated and with blueprints for destruction.A robust ground operation is needed to destroy IS strongholds. A powerful force deployment, consisting of US and NATO troops, will demonstrate true staying power – shifting the broader equilibrium away from sectarian violence – with Iran at the fulcrum – and toward regional stability buoyed by the United States. The legacy of Islamic terrorism demonstrates that half-measures are self-defeating, as they will only highlight American weakness and leave the door open for wider insurrection. Indeed, IS will continue to attract foreign fighters unless and until it can no longer sustain – or, more aptly, portray a picture of – clear success.Western refusal to confront radical Islam has created the climate in which Islamists on all sides have proceeded ruthlessly and efficiently – without disturbance. Serious investigation into the Muslim mindset – and the application of that scholarship to warfare – will translate into decisive victory on the battlefield.The author served for 28 years as an analyst covering Middle Eastern affairs at the Office of the Secretary of Defense. Joseph Raskas is a combat veteran of the Israel Defense Forces and currently a Fellow participating in The Public Interest Fellowship.