Air Force A-10 Thunderbolt refuels from a KC-135 Stratotanker over Iraq, Nov. 29, 2016, in support of Operation Inherent Resolve. (Air Force Photo/Senior Airman Jordan Castelan)

(CNSNews.com) - The number of weapons the U.S.-led air war has fired against the Islamic State in Iraq and Syria since 2014 (over 63,061) is approximately twice the maximum number of fighters ISIS had in Iraq and Syria as of the beginning of that air war (31,500), according to numbers released separately by the Department of Defense and the Central Intelligence Agency.

Yet, if ISIS is denied all of the territory it once controlled in Iraq and Syria, even the Obama administration is not arguing that the terror threat it poses to Europe and the United States will end.

In fact, FBI Director James Comey warned Congress in September that the territorial defeat of ISIS in Iraq and Syria will cause “killers” to flow out of those nations in the hope of murdering people in Western Europe and the United States.

“The so-called caliphate will be crushed,” Comey said. “The challenge will be through the fingers of that crush are going to come hundreds of very, very dangerous people. They will not all die on the battlefield in Syria and Iraq. There will be a terrorist diaspora sometime in the next two to five years like we've never seen before.

“We must prepare ourselves and our allies, especially in Western Europe, to confront that threat,” Comey said. “Because when ISIL is reduced to an insurgency and those killers flow out, they will try to come to Western Europe and try to come here to kill innocent people. We have to keep our eye on it and be ready for it.”

Brett McGurk, Obama’s special envoy for the coalition fighting ISIS, predicted to State Department Inspector General Steve Linick in an October interview--as summarized in a subsequent IG report--“that the terrorist threat posed by ISIL globally could last well into the next decade, even after it is defeated in Iraq and Syria.”

“Asked about the threat ISIL poses, Special Presidential Envoy McGurk said the challenge to the international community was unprecedented,” said the IG report. “More than 40,000 foreign fighters have gone into Iraq and Syria—twice as many as went to Afghanistan during the 1980s—and the ease of traveling to the Middle East compared to Afghanistan, coupled with advances in global communications systems have facilitated ISIL’s ability to organize and carry out attacks.”

CIA Director John Brennan, meanwhile, told Congress on June 16 that ISIS already had many thousands of fighters outside Iraq and Syria.

Brennan said that “as the pressure mounts on ISIL, we judge that it will intensify its global terror campaign to maintain its dominance of the global terrorism agenda.”

“The numbers of ISIL fighters now far exceeds what al Qaeda had at its height,” Brennan testified. "We're talking about tens of thousands of individuals."

“Unfortunately, despite all our progress against ISIL on the battlefield and in the financial realm, our efforts have not reduced the group’s terrorism capability and global reach,” Brennan said. “The resources needed for terrorism are very modest, and the group would have to suffer even heavier losses of territory, manpower, and money for its terrorist capacity to decline significantly.

“Moreover, the group’s foreign branches and global networks can help preserve its capacity for terrorism regardless of events in Iraq and Syria,” he said. “In fact, as the pressure mounts on ISIL, we judge that it will intensify its global terror campaign to maintain its dominance of the global terrorism agenda.

“Since at least 2014,” Brennan said, “ISIL has been working to build an apparatus to direct and inspire attacks against its foreign enemies, resulting in hundreds of casualties. The most prominent examples are the attacks in Paris and Brussels, which we assess were directed by ISIL’s leadership.”

Brennan also warned the committee that ISIL may see the flow of refugees as “a means of infiltrating operatives into the West.”

“We judge that ISIL is training and attempting to deploy operatives for further attacks,” he said. “ISIL has a large cadre of Western fighters who could potentially serve as operatives for attacks in the West. And the group is probably exploring a variety of means for infiltrating operatives into the West, including refugee flows, smuggling routes, and legitimate methods of travel.”

The U.S.-led air war against ISIS in Iraq and Syria began in August 2014. On Sept. 10, 2014, President Barack Obama gave a nationally televised address explaining the military campaign.

“I can announce that America will lead a broad coalition to roll back this terrorist threat,” Obama said.

“Our objective is clear,” he said. “We will degrade, and ultimately destroy, ISIL through a comprehensive and sustained counterterrorism strategy.

“First, we will conduct a systematic campaign of airstrikes against these terrorists,” Obama said.

The next day, the Washington Post published a story quoting a CIA spokesman stating that the CIA then assessed that ISIL could have up to 31,500 fighters in Iraq and Syria.

“CIA assesses the Islamic State of Iraq and the Levant (ISIL) can muster between 20,000 and 31,500 fighters across Iraq and Syria, based on a new review of all-source intelligence reports from May to August, an increase from our previous assessment of at least 10,000 fighters,” the CIA spokesman told the Post. “This new total reflects an increase in members because of stronger recruitment since June following battlefield successes and the declaration of a caliphate, greater battlefield activity, and additional intelligence.”

Since then, according to the CIA’s latest public assessment, the number of ISIS fighters in Iraq and Syria has declined to a maximum of 22,000.

“The latest declassified estimate of ISIL manpower in Iraq and Syria is 18,000 to 22,000 fighters, as cited by Director Brennan in his June testimony to the Senate Select Committee on Intelligence,” a CIA spokesman told CNSNews.com on Dec. 1.

During Brennan’s June 16 testimony in the Senate intelligence committee, Sen. Dianne Feinstein asked him to estimate the current number of ISIS fighters. He noted that the number in Iraq and Syria may have climbed as high as 33,000 in 2015 and then dropped to 18,000 to 22,000 by the time of his testimony.

But that did not include the many thousands of ISIS fighters outside of Iraq and Syria.

“Right now, we estimate within the Syria-Iraq area, I think, it's between 18,000, 22,000 fighters,” Brennan testified. “And that's down significantly from our estimates last year, where we estimated they may have had as many 33,000 or so fighters.”

But then Brennan said: “In Libya, numbers range could be from 5,000 to 8,000 or so.”

“Inside of Egypt,” he told the committee, “there are several hundreds, if not over a thousand, hard-core fighters inside of the Sinai that are a combination of individuals who were formerly of Ansar Beit al Maqdis, as well as others who have joined.

“Inside of Yemen,” he said, “you have several hundred.”

“In Afghanistan, Pakistan, it's in the hundreds,” he said.

“Nigeria, at this stage, you probably have maybe 7,000 or so,” Brennan said.

“Again,” he said, “there are hard-core fighters, there are adherents, there are logistics specialists, facilitators and others.

“But the numbers are significant,” he said.

In October 2014, a month after Obama gave his speech announcing the coalition against ISIS, the Defense Department named the coalition’s campaign “Operation Inherent Resolve” (OIR).

“Since the beginning of OIR, the Coalition has conducted more than 128,725 sorties and employed over 63,061 weapons,” a spokesman for the Combined Joint Task Force-Operation Inherent Resolve (CJTF-OIR) told CNSNews.com in a Dec. 7 email.

(The Air Power Summary for November published by the U.S. Air Forces Central Command reports a comparable number. It says that from August 2014 through November 2016, Operation Inherent Resolve had released 62,788 weapons in Iraq and Syria.)

DOD defines a sortie as the “combat mission of an individual aircraft, starting when the aircraft takes off and ending on its return.” An aircraft flying a “sortie” may or may not discharge a weapon, and an aircraft flying a reconnaissance mission is counted as a sortie, which explains why the number of sorties over Iraq and Syria (128,725) exceeds the number of weapons employed (63,061).

The 128,725 sorties, the CJTF-OIR spokesman said, “includes all missions to include reconnaissance to develop targets. We spend considerable time researching and developing target lists to ensure maximum effect against Da’esh and to minimize the potential for civilian casualties.”

The "over 63,061weapons" that the coalition’s air war has fired at ISIS targets in Iraq and Syria since 2014 is about double the CIA’s assessment of a maximum of 31,500 ISIS fighters in Iraq and Syria as of September 2014 when President Obama announced the campaign.

CNSNews.com asked the Defense Department how many ISIS fighters had been killed by the weapons the coalition had dropped.

“We don’t track the number of Da’esh killed,” the CJTF-OIR spokesman responded.

The DOD has published a chart stating that 31,900 targets had been “damaged/destroyed” by Operation Inherent Resolve as of Sept. 26, 2016. According to the chart, these included 164 tanks; 388 HMMWVs; 2,050 staging areas; 7,948 buildings; 8,638 fighting positions; 2,638 oil infrastructure; and 10,074 “other targets.”

Another chart published by DOD summarizes the “strikes” that the coalition had carried out as of Dec. 2, 2016. DOD defines a “strike” as “one or more kinetic events that occur in roughly the same geographic location to produce a single, sometimes cumulative effect for that location.”

“So having a single aircraft deliver a single weapon against a lone ISIL vehicle is one strike, but so is multiple aircraft delivering dozens of weapons against a group of buildings and vehicles and weapon systems in a compound, for example, having the cumulative effect of making that facility (or facilities) harder or impossible to use,” says DOD.

As of Dec. 2, 2016, according to the chart, Operation Inherent Resolve had carried out 16,592 “strikes” of which 10,590 hit targets in Iraq and 6,002 hit targets in Syria.

The U.S. conducted 12,876 of the strikes (7,183 in Iraq and 5,693 in Syria). Coalition partners conducted the other 3,716 (3,407 in Iraq and 309 in Syria).

Since this air campaign started on Aug. 8, 2014, the U.S. has admitted 45,482 refugees from Syria and Iraq, according to the State Department.

16,981 were from Syria. Of these, 16,534—or 97.4 percent—were Sunni Muslims.

28,501 were from Iraq. Of these, 12,454—or 43.7 percent--were Sunni Muslims.

On March 17 of this year, Secretary of State John Kerry said that ISIS, which espouses Sunni Islam, was committing genocide against Christians, Yezidis and Shia Muslims.