This article originally was published by Foxnews.com.

The violent conclusion to the Australian hostage taking terrorist siege was inevitable. The terrorist Man Haron Monis was killed as the Sydney police swat team stormed the café. Even though two hostages were killed, the Sydney police had no choice but to act. After a siege lasting nearly 17 hours, police had good reason to believe that the self-anointed "Sheik" Haron Monis was going to make good on his threat to detonate the bombs he claimed to have unless his demands were met.

There had been an open line between a police hostage negotiator with the terrorist for much of that time but with up to 10 hostages remaining captive, it was feared that the terrorist was going to become a suicide bomber and thus kill everyone in the café. The Sydney police are now involved in investigating and reconstructing the time line of entire incident. But there is no doubt that the Australian police saved the lives of many more hostages.

There should be no doubt that this was a pure act of Islamic terrorism despite ludicrous assertions by some commentators that his "motivations" were unknown. We will see all sorts of "explanations" that because his rap sheet included indictments for sexual assault and murder, he was not really an Islamic terrorist but someone who was simply mentally unstable. Well, the same rationale could be said for all terrorists. After all, who in their right mind would want to kill innocent civilians because of their religious beliefs?

Islamic extremists do. And to deny their radical Islamic motivation—as our own government has done repeatedly in refusing to classify Islamic terrorist attacks as such as in the case of the massacre carried out by Major Nidal Hassan—is a guarantee that such acts will continue to be perpetuated especially by lone wolf terrorists. Australian police are investigating to determine if Monis acted alone or whether he acted in concert with other Islamic extremists or even at the behest of ISIS itself.

Last month, Monis pledged his allegiance to ISIS and renounced his Shiite heritage in an online posting that since has been taken down. Our organization, the Investigative Project on Terrorism, retrieved the page and translated it. Monis wrote:

"Pledge of allegiance [to ISIS] of Sheikh Haron"

"Allegiance with Allah and His Messenger, and the Commander of the Faithful – I pledge allegiance to Allah and His Messenger and the Caliph of the Muslims"

"Praise be to Allah and prayers and peace be upon our Prophet Muhammad, his family and all his companions, and those who follow them and peace be upon the Commander of the Faithful, the Caliph of the Muslims, the Imam of our current era, and praise be to Allah, who made for us a Caliph of the Earth and an imam who summons us to Islam and holds fast to the Rope of Allah Almighty and praise be to Allah that I have had the honor to pledge allegiance to the Imam of our time. Those who swear allegiance to the Caliph of the Muslims are just swearing allegiance to Allah and His Messenger…."

His website also contained rants against the Australian government for their involvement in Iraq and Afghanistan.

Australian intelligence was aware of Monis early on and had an extensive file on him based on his prior radical Islamic activities in Australia and electronic surveillance of his communications with Islamic terrorists overseas.

The terrorist incident in Sydney certainly indicates parallels with the calls for individually driven terrorist attacks by Islamic radicals throughout the West. These calls grew in prominence with Inspire magazine, put out by Al Qaeda in the Arabian Peninsula (AQAP) led by Anwar Al-Awlaki until he was killed by a U.S. drone. In calling for Muslims living in western countries to carry out lone wolf terrorist attacks, ISIS has copied the same playbook as AQAP in calling for local attacks whenever and where ever possible. These attacks are happening all over the world now, especially fueled beyond the Internet by the rise of social media which has pushed the message of Islamic terrorism virtually as fast as the speed of light. In the past two years alone, there have been more than 100 attempted or successful ISIS inspired Islamic terrorist attacks in Europe and the United State From Belgium to France to Oklahoma City, no place is immune from Islamic terrorism, whether it be from returning ISIS veterans or just those radical Muslims living in the West who are motivated to carry out attacks.

Moreover, it is a lethal mistake for western leaders to differentiate ISIS from other Islamic terrorist groups such as Hamas, Hizballah, Boko Haram, or Al Shabaab. Those Islamic terrorist groups are motivated by the same underlying motivations behind ISIS: to kill as many of their infidel enemies as possible and impose Islamic supremacy. The only difference is that ISIS has declared itself to be a global caliphate; the other groups are focused on becoming regional caliphates. But their genocidal agenda and tactics are no different than those of ISIS. The only reason Hamas has not been as successful as ISIS in killing its infidel enemies is that Israel has been able to stop Hamas from carrying out acts of mass murder, even though Hamas tried this past summer when it launched more than 6,000 rockets and missiles at Israel in an effort to kill as many civilians as possible. Nigeria on the other hand has been unable to stop the horrific successful attacks by Boko Haram in which more than 300 Nigerians have been slaughtered in the past year alone.

Australian intelligence agencies probably had the best handle on the domestic threat by Islamic extremists as evidenced by their successful interruption of major plots in the past year. Those plots included a plan to behead Australian civilians and a conspiracy to bomb Australian targets. But those were plots planned by conspiracies of multiple extremists. Today's incident, however, shows the difficulties of stopping lone wolf attacks. What we are witnessing is not the rise of radical Islam. It is only an extension of the rise of radical Islam unleashed by the 9/11 attacks. The difference is that this phase is not directed by centralized organizations. Islamic terrorism has now become decentralized, creating a new challenge for western intelligence agencies. It creates extraordinary pressure to come up with new methods to monitor internal threats which are also a technical challenge as it means monitoring meta data of social media. But the most dangerous and counterproductive act would be to deny that Islamic terrorist attacks are what they are: Islamic terrorist attacks.

Steven Emerson is executive director of the Investigative Project on Terrorism and the executive producer of a new documentary about the Muslim Brotherhood in America "Jihad in America: the Grand Deception."