Analysts say it's taken its black-market operations and leadership structure to places like Africa and South Asia.

Some U.S. foreign policy veterans are warning that the political debate in Washington is hampering hopes of meeting the challenge to U.S. security posed by ISIS and finally closing America's book on Iraq.

By taking the city, ISIS tightened control of the Anbar province and gained a base of operations only 70 miles from Baghdad.

"We don't want to do anything to blow this up horribly and, frankly, push the Iraqis further into the arms of the Iranians, but I do think we need to do everything we can to maximize our pressure and make sure that we're not going to have American troops close to harm, because [the Iraqi government] isn't willing to bring the Sunnis into the government and into the military, " the congressman said. Large numbers of Daesh were killed in the last few days and will be in the next days because that seems to be the only thing they understand.

Before Ramadi fell, the central focus of the U.S. and its allies was retaking Mosul, the first major Iraqi city to fall to ISIS last summer. NPR reached restaurant owner Sameh Abdulkareem by phone, and he told us that ISIS says it's in Ramadi for the long haul. It also quickly overshadowed the White House’s weekend disclosure of a daring Special Forces raid that killed a key ISIL leader inside Syria.

Its fall strengthens the jihadists hold in Al Anbar, after their recent military setback in Tikrit.

But that approach failed to prevent the fall of Ramadi, where militias backed by Iran will now take the lead in any counter-attack and reinforce their influence in Iraq.

"They have performed as you would expect an army infantry maneuver unit to perform - exercising good command and control in the field,” he said. Iran and the Shiite militias would be threatened by any effort on Abadi’s part to form partnerships with moderate Sunnis, and this situation helped to contribute to the insecurity at Ramadi.

In a sign of the deep suspicion common in Iraq, he even speculates that Iraq's Shiite-led government weakened local Sunni fighters on purpose, giving the government an excuse to send in Shiite fighters. Nearly a quarter million are dead, literally half the population has been displaced, President Assad is holding onto power by using barrel bombs and other monstrous means of "counterinsurgency" warfare - and the strongest opposition force pitted against him is now ISIL, followed by the al-Qaeda affiliate al-Nusra.

Ramadi is dominated by Sunni Muslims. Yet Obama emphasized his paramount concern: "American forces will not have a combat mission - we will not get dragged into another ground war in Iraq". So we are seeing now an intermittent type of conflict that pops from one area to the other with disastrous consequences for the population and Syria’s geopolitical risks. That reinforced the idea that ISIL cannot be defeated without American help, Pollack said.

Even more worrying than ISIS’s successful offense [against Ramadi] is how quickly Iraqi security forces abandoned the city.

"Ramadi runs the danger of reversing Tikrit - it has the potential to change the narrative back,” Pollack said. And tonight, this. These are the Iraqi fighters who were left behind, racing to be air lifted to safety. However, some analysts have argued that militias and paramilitaries constitute the larger portion of the forces fighting ISIL, thus setting the stage for the Iraqi armed forces becoming integrated into the Shiite fighting force, instead of vice versa.

The Wednesday before, Iraq veteran and former Marine Gen. James Mattis told The Daily Caller, "The president came out and said we didn’t have a strategy on this [ISIS]".