Osama bin Laden, Abu Musab al-Zarqawi, and Abu Ayyub al-Masri—what did they all have in common? A dream of an Islamic State, a real caliphate. But like the dreams of many, they get lost in translation or in their implementation. Their organizations were comprised of nothing more than murderers who lived in the caves of Afghanistan and Yemen, or in the back alleys and basements of Iraq’s busy cities. Analytically speaking, they weren’t a real threat to our national security, not even close. More of a passive nuisance compared to the real dangers of the 21st-century world such as the ‘dragon’ or the ‘bear’ in the east.

Under the leadership and guidance of Abu Bakr al-Baghdadi, ISIS transformed from a terrorist group hiding in the shadows to a guerrilla army with world renown. They swept through Syria and Iraq like a plague, virtually untouched. It was nothing less than a blitzkrieg. The coalition scrambled to react, but it was too late. Somehow, approximately 30,000 ISIS fighters (according to the CIA) gained control of large Iraqi cities such as Mosul, Ramadi, Tikrit, and Fallujah in 2014, within a period of just seven months.

Thousands of ISIS fighters sat at the doorstep of Baghdad and Erbil, ready to invade. They’ve done in just two short years what every other Islamic terrorist group has failed to do: create an Islamic State. And not just through a benign declaration, but through action. They now control large regions in both Iraq and Syria, tens of thousands of loyal fighters, growing alliances with other organizations around the world, and even their own capital city in Syria. And at the time of this writing, approximately 10 million civilians live under their control. Either the CIA has grossly underestimated their numbers, or these are some of the most proficient fighters the world has ever seen.

The United States and its Western allies will never amass the same fighting force that existed during Operation Iraqi Freedom, sent to fight both Saddam and the growing Iraqi insurgency. ISIS knows this. They have the freedom to operate, invade, and expand with a relative freedom that other jihadi groups have never experienced.

From 2004 to 2006, when I was deploying with the Rangers to Iraq, one could immediately recognize that the vacuum left by Saddam and his Ba’ath Party cronies gave rise to the insurgency and al-Qaeda in Iraq. They did not exist there beforehand. And they never would have existed under the rule of Saddam. The U.S. and its coalition created another vacuum in Libya with the removal of Qaddafi, which massively destabilized the country. Vacuums, not dictators, create Islamic extremism in the Middle East. And nobody creates power vacuums better than the United States.

Libya: The next U.S. battleground against ISISIn February of 2016, I was approached by a private military company out of Europe, which shall stay nameless. The company, along with a few others, were contacted by the new Libyan government seeking help for their ISIS problems. I run a small recruiting firm on the side that specializes in collaborating with PMCs during the contract bid process, in which I find them military contractors beforehand, usually the program managers and team leaders that are in charge of the operations. Executives of the company traveled to Tripoli to meet with their government, but ultimately lost the contract to another player.

After a little bit of research, “ISIS problems” turned out to be an understatement. Six thousand. That’s the U.S. intelligence community’s estimate for how many ISIS fighters are in Libya. And there are thousands more from other militant groups who are ready to pledge their allegiance to the Islamic State. In terms of geography, ISIS controls a region the size of Tennessee in the area between Tripoli and Benghazi (see map above).

Why has ISIS failed miserably in its attempts to gain ground in places like Yemen and Afghanistan, but are seeing massive successes in Libya? I believe it still comes down to power vacuums. Libya has them, others do not. In Yemen, al-Qaeda in the Arabian Peninsula (AQAP), is still the dominant player. It’s gained large swathes of land and has even gained the trust of the local population, whereas the Islamic State is known to subjugate civilians under its control.