Pentagon chief: ISIS 'beyond anything we have seen'By Chelsea J. Carter and Azadeh Ansari, CNNUpdated 10:37 AM ET, Fri August 22, 2014Just WatchedPentagon's chilling ISIS warningreplayMore Videos ...Pentagon's chilling ISIS warning 01:46Story highlightsISIS is "a cancer" that can spread into Europe and the U.S., Sen. John McCain says"This is beyond anything we have seen," Defense Secretary Chuck Hagel saysDempsey says ISIS can't be defeated without addressing its presence in SyriaU.S. Central Command has conducted 51 airstrikes near the Mosul DamAmerica's top defense officials left open the possibility of targeting ISIS fighters in Syria, saying during a news briefing Thursday that it was not enough to just hit the extremist group in Iraq. Defense Secretary Chuck Hagel and Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, stopped short of calling for U.S. military action in eastern Syria, an ISIS stronghold. "Can they be defeated without addressing that part of the organization that resides in Syria? The answer is no," Dempsey said during the briefing at the Pentagon. Repeatedly pushed by reporters about whether that meant operations against ISIS in Syria, Hagel said, "We're looking at all options." While it's unclear what those options may be, Hagel said the United States is "very clear-eyed" about ISIS, which calls itself the Islamic State but also is known as the Islamic State in Iraq and Syria. "They are beyond just a terrorist group. They marry ideology, a sophistication of strategic and tactical military prowess," Hagel said. Just WatchedWill ISIS execution change Iraq strategy?replayMore Videos ...Will ISIS execution change Iraq strategy? 05:52PLAY VIDEOJust WatchedWho is James Foley's executioner?replayMore Videos ...Who is James Foley's executioner? 00:10PLAY VIDEOJust WatchedAirstrikes hit Iraq, Obama condemns journalist's murderreplayMore Videos ...Airstrikes hit Iraq, Obama condemns journalist's murder 04:15PLAY VIDEOThe ISIS terror threat 47 photosThe ISIS terror threat 47 photosA Kurdish marksman looks over a destroyed area of Kobani, Syria, on Friday, January 30. Kobani, also known as Ayn al-Arab, had been under assault by ISIS since mid-September.Hide Caption 1 of 47The ISIS terror threat 47 photosSmoke billows in the background as Kurdish Peshmerga fighters take position in Kirkuk, Iraq, on January 30.Hide Caption 2 of 47The ISIS terror threat 47 photosRelatives of Moaz al-Kassasbeh, a Jordanian pilot who was captured in December by ISIS militants, protest in front of the Royal Palace in Amman, Jordan, on Wednesday, January 28. ISIS has threatened to kill al-Kassasbeh and Japanese hostage Kenji Goto if Jordan does not release Sajida al-Rishawi, a convicted would-be suicide bomber.Hide Caption 3 of 47The ISIS terror threat 47 photosKurdish people celebrate in Suruc, Turkey, near the Turkish-Syrian border, after ISIS militants were expelled from Kobani, Syria, on Tuesday, January 27.Hide Caption 4 of 47The ISIS terror threat 47 photosCollapsed buildings are seen in Kobani on January 27 after Kurdish forces took control of the town from ISIS. ISIS has been making advances in Iraq and Syria as it seeks to create an Islamic caliphate in the region.Hide Caption 5 of 47The ISIS terror threat 47 photosJunko Ishido, mother of Japanese journalist Kenji Goto, reacts during a news conference in Tokyo on Friday, January 23. ISIS has already claimed to kill another Japanese hostage, Haruna Yukawa.Hide Caption 6 of 47The ISIS terror threat 47 photosISIS militants are seen through a rifle's scope during clashes with Peshmerga fighters in Mosul, Iraq, on Wednesday, January 21.Hide Caption 7 of 47The ISIS terror threat 47 photosAn elderly Yazidi arrives in Kirkuk, Iraq, on Saturday, January 17, after being released by ISIS. The militant group released about 200 Yazidis who were held captive for five months in Iraq. Almost all of the freed prisoners were in poor health and bore signs of abuse and neglect, Kurdish officials said.Hide Caption 8 of 47The ISIS terror threat 47 photosAn identification card lies in the dirt in the Hardan village in northern Iraq on Monday, December 22. A handful of Yazidis who fled when ISIS overran the town in August returned after Kurdish fighters drove the extremists out.Hide Caption 9 of 47The ISIS terror threat 47 photosSmoke billows behind an ISIS sign during an Iraqi military operation to regain control of the town of Sadiyah, about 95 kilometers (60 miles) north of Baghdad, on Tuesday, November 25.Hide Caption 10 of 47The ISIS terror threat 47 photosFighters from the Free Syrian Army and the Kurdish People's Protection Units join forces to fight ISIS in Kobani on Wednesday, November 19.Hide Caption 11 of 47The ISIS terror threat 47 photosA picture taken from Turkey shows smoke rising after ISIS militants fired mortar shells toward an area controlled by Syrian Kurdish fighters near Kobani on Monday, November 3.Hide Caption 12 of 47The ISIS terror threat 47 photosIraqi special forces search a house in Jurf al-Sakhar, Iraq, on Thursday, October 30, after retaking the area from ISIS.Hide Caption 13 of 47The ISIS terror threat 47 photosISIS militants stand near the site of an airstrike near the Turkey-Syria border on Thursday, October 23. The United States and several Arab nations have been bombing ISIS targets in Syria to take out the militant group's ability to command, train and resupply its fighters.Hide Caption 14 of 47The ISIS terror threat 47 photosKurdish fighters walk to positions as they combat ISIS forces in Kobani on Sunday, October 19.Hide Caption 15 of 47The ISIS terror threat 47 photosA U.S. Air Force plane flies above Kobani on Saturday, October 18. Hide Caption 16 of 47The ISIS terror threat 47 photosHeavy smoke rises in Kobani following an airstrike by the U.S.-led coalition on October 18.Hide Caption 17 of 47The ISIS terror threat 47 photosCundi Minaz, a female Kurdish fighter, is buried in a cemetery in the southeastern Turkish town of Suruc on Tuesday, October 14. Minaz was reportedly killed during clashes with ISIS militants in nearby Kobani.Hide Caption 18 of 47The ISIS terror threat 47 photosTurkish police officers secure a basketball stadium in Suruc on October 14. Some Syrian Kurds were held there after crossing from Syria into Turkey. Tens of thousands of people fled Kobani to escape ISIS.Hide Caption 19 of 47The ISIS terror threat 47 photosKiymet Ergun, a Syrian Kurd, celebrates in Mursitpinar, Turkey, after an airstrike by the U.S.-led coalition in Kobani on Monday, October 13.Hide Caption 20 of 47The ISIS terror threat 47 photosAlleged ISIS militants stand next to an ISIS flag atop a hill in Kobani on Monday, October 6. Hide Caption 21 of 47The ISIS terror threat 47 photosIn this photo released by the U.S. Air Force on Saturday, October 4, a U.S. Navy jet is refueled in Iraqi airspace after conducting an airstrike against ISIS militants.Hide Caption 22 of 47The ISIS terror threat 47 photosA Kurdish Peshmerga soldier who was wounded in a battle with ISIS is wheeled to the Zakho Emergency Hospital in Duhuk, Iraq, on Tuesday, September 30.Hide Caption 23 of 47The ISIS terror threat 47 photosSyrian Kurds wait near a border crossing in Suruc as they wait to return to their homes in Kobani on Sunday, September 28.Hide Caption 24 of 47The ISIS terror threat 47 photosTomahawk missiles, intended for ISIS targets in Syria, fly above the Persian Gulf after being fired by the USS Philippine Sea in this image released by the U.S. Navy on Tuesday, September 23.Hide Caption 25 of 47The ISIS terror threat 47 photosTurkish Kurds clash with Turkish security forces during a protest near Suruc on Monday, September 22. According to Time magazine, the protests were over Turkey's temporary decision to close the border with Syria.Hide Caption 26 of 47The ISIS terror threat 47 photosSyrian Kurds fleeing ISIS militants wait behind a fence in Suruc on Sunday, September 21.Hide Caption 27 of 47The ISIS terror threat 47 photosA elderly man is carried after crossing the Syria-Turkey border near Suruc on Saturday, September 20.Hide Caption 28 of 47The ISIS terror threat 47 photosA Kurdish Peshmerga fighter launches mortar shells toward ISIS militants in Zumar, Iraq, on Monday, September 15.Hide Caption 29 of 47The ISIS terror threat 47 photosKurdish Peshmerga fighters fire at ISIS militant positions from their position on the top of Mount Zardak, east of Mosul, Iraq, on Tuesday, September 9. Hide Caption 30 of 47The ISIS terror threat 47 photosIraqi volunteer fighters celebrate breaking the Amerli siege on Monday, September 1. ISIS militants had surrounded Amerli, 70 miles north of Baquba, Iraq, since mid-June.Hide Caption 31 of 47The ISIS terror threat 47 photosKurdish Peshmerga forces stand guard at their position in the Omar Khaled village west of Mosul on Sunday, August 24. Hide Caption 32 of 47The ISIS terror threat 47 photosKurdish Peshmergas fight to regain control of the town of Celavle, in Iraq's Diyala province, on August 24.Hide Caption 33 of 47The ISIS terror threat 47 photosPeshmerga fighters stand guard at Mosul Dam in northern Iraq on Thursday, August 21. With the help of U.S. military airstrikes, Kurdish and Iraqi forces retook the dam from ISIS militants on August 18. A breach of the dam would have been catastrophic for millions of Iraqis who live downstream from it.Hide Caption 34 of 47The ISIS terror threat 47 photosDisplaced Iraqis receive clothes from a charity at a refugee camp near Feeshkhabour, Iraq, on Tuesday, August 19.Hide Caption 35 of 47The ISIS terror threat 47 photosPeshmerga fighters inspect the remains of a car that reportedly belonged to ISIS militants and was targeted by a U.S. airstrike in the village of Baqufa, north of Mosul, on August 18.Hide Caption 36 of 47The ISIS terror threat 47 photosKurdish Peshmerga fighters fire at ISIS in Khazair, Iraq, on Thursday, August 14. Hide Caption 37 of 47The ISIS terror threat 47 photosAziza Hamid, a 15-year-old Iraqi girl, cries for her father while she and some other Yazidi people are flown to safety Monday, August 11, after a dramatic rescue operation at Iraq's Mount Sinjar. A CNN crew was on the flight, which took diapers, milk, water and food to the site where as many as 70,000 people were trapped by ISIS. But only a few of them were able to fly back on the helicopter with the Iraqi Air Force and Kurdish Peshmerga fighters.Hide Caption 38 of 47The ISIS terror threat 47 photosThousands of Yazidis are escorted to safety by Kurdish Peshmerga forces and a People's Protection Unit in Mosul on Saturday, August 9.Hide Caption 39 of 47The ISIS terror threat 47 photosThousands of Yazidi and Christian people flee Mosul on Wednesday, August 6, after the latest wave of ISIS advances.Hide Caption 40 of 47The ISIS terror threat 47 photosA Baiji oil refinery burns after an alleged ISIS attack in northern Selahaddin, Iraq, on Thursday, July 31.Hide Caption 41 of 47The ISIS terror threat 47 photosA Syrian rebel fighter lies on a stretcher at a makeshift hospital in Douma, Syria, on Wednesday, July 9. He was reportedly injured while fighting ISIS militants.Hide Caption 42 of 47The ISIS terror threat 47 photosPeshmerga fighters clean their weapons at a base in Tuz Khormato on June 25.Hide Caption 43 of 47The ISIS terror threat 47 photosNew army recruits gather in Najaf, Iraq, on Wednesday, June 18, following a call for Iraqis to take up arms against Islamic militant fighters. Hide Caption 44 of 47The ISIS terror threat 47 photosKurdish Peshmerga forces, along with Iraqi special forces, deploy their troops and armored vehicles outside of Kirkuk, Iraq, on June 12.Hide Caption 45 of 47The ISIS terror threat 47 photosChildren stand next to a burnt vehicle during clashes between Iraqi security forces and ISIS militants in Mosul on Tuesday, June 10.Hide Caption 46 of 47The ISIS terror threat 47 photosCivilians from Mosul escape to a refugee camp near Irbil, Iraq, on June 10. Hide Caption 47 of 47EXPAND GALLERY"This is beyond anything we have seen, and we must prepare for everything. And the only way you do that is that you take a cold, steely hard look at it and get ready." Speaking at a town hall meeting in Arizona, Republican Sen. John McCain, who has advocated for strikes against ISIS in Syria, said the extremists were "an enemy that must be defeated. Not stopped, but defeated.""It is a cancer which has spread throughout that region and can spread into Europe and into the United States of America," McCain said. His phrase echoed the term President Barack Obama used Wednesday to describe the terrorist group.Hagel offered his condolences to the family of American journalist James Foley, whose execution at the hands of ISIS was captured on video and posted online this week as a warning to the United States.The group threatened the life of another American hostage, believed to be journalist Steven Sotloff, if the United States did not end its airstrikes in Iraq.The threat has done little to curb U.S. military operations in Iraq. On Thursday, American warplanes pounded ISIS targets near Mosul Dam, where Iraqi forces have been battling to retake control of the area. A total of six airstrikes hit ISIS positions, according to the Defense Department. The strikes destroyed or damaged three ISIS Humvees, one ISIS vehicle and multiple locations where improvised explosives had been placed, the U.S. military said. Obama ordered targeted airstrikes in Iraq this month to protect U.S. personnel and facilities as well as minorities being brutalized by ISIS. Since August 8, the U.S. military has carried out 90 airstrikes, 57 of them in support of Iraqi forces near the Mosul Dam, according to the Defense Department.Mosul Dam is the largest in the country, and Iraqi and U.S. officials fear that a breach in the dam would threaten the lives of millions of Iraqis who live downstream in Mosul and Baghdad.Just WatchedUncovering intelligence from ISIS videoreplayMore Videos ...Uncovering intelligence from ISIS video 02:05PLAY VIDEOJust WatchedISIS sells $3M of black-market oil dailyreplayMore Videos ...ISIS sells $3M of black-market oil daily 02:40PLAY VIDEOJust WatchedHagel: ISIS 'beyond a terrorist group'replayMore Videos ...Hagel: ISIS 'beyond a terrorist group' 01:27PLAY VIDEOJust WatchedJames Foley's work as a war correspondentreplayMore Videos ...James Foley's work as a war correspondent 02:30PLAY VIDEOU.S. airstrikes played a role helping Kurdish and Iraqi forces retake control of the dam, pushing back ISIS militants who seized it. With the dam clear of ISIS fighters, Iraqi forces are expanding their area of control, the Defense Department said. The fighting and efforts by ISIS militants to take over towns in northern Iraq have forced as many as 1.2 million Iraqis from their homes so far this year, according to UNHCR estimates.On Thursday, Kurdistan's regional government praised the assistance provided by the United States and the international community. "We are grateful to the men and women of the American armed forces who have carried out these decisive attacks against the terrorist forces of ISIS," said a statement from the regional government.Nechirvan Barzani, the prime minister of the regional government, described the beheading of Foley as "a horrendous act committed with utter disregard for human life.""Like Mr. Foley, several hundred innocent members of the Yazidi and Christian communities have been killed in the same manner," Barzani said in a statement Thursday. "There is no way to overstate the extent of this inhumanity, and it illustrates the true, dark nature of the terrorists that we are confronting."Also Thursday, a third French aid flight headed to Irbil, according to the French foreign ministry. The aid includes 21 metric tons of food, tents, medical supplies and other basic necessities. France has delivered 58 metric tons of aid since it started its humanitarian flights on August 15, the ministry said. What will it take to beat ISIS militants?Foley's final months: Mock executions, failed rescue attemptWho's doing what to fight ISISIraqVisit CNN ArabicGet all the latest news and updates on Iraq in Arabic by visiting CNN Arabic.Beheading recalls past horrorsThe beheading of American journalist James Foley by ISIS militants brings into focus once again the risks faced by reporters in modern conflicts.James Foley, 'brave and tireless' journalistWhen war reporter James Foley wasn't writing for GlobalPost or recording video for AFP, he occasionally shared stories on his own blog, aptly titled "A World of Troubles." Video shows ISIS beheading journalistA video released by ISIS shows the beheading of U.S. journalist James Foley and threatens the life of another American if President Obama doesn't end military operations in Iraq. Can this man keep Iraq together?"May God help you," the speaker of Iraq's parliament told Haider al-Abadi the day he was nominated prime minister. Why intervene in Iraq, not Syria?The answers to this question lie in some clear differences in the two conflicts.Could U.S. anger Sunnis?Framing the intervention in religious terms bolsters theories of U.S. bias, says Fahad Nazer.Yazidi refugees braced for life in exileThey are the faces of an entire community on the run. Exhausted Yazidi escape ISISIn an exodus of almost biblical proportions, thousands trudge across a river to escape killers belonging to the Islamic State in Iraq and Syria, or ISIS.Yazidi family's harrowing flightTheirs were the faces that stood out in the chaotic helicopter evacuation off the Sinjar Mountains.Photos: Iraqi refugees fleeing ISISBrowse through photos of thousands of refugees trudging across a river to escape ISIS.'Heroic' mission to rescue YazidisThe face of 15-year-old Aziza -- rescued from Mount Sinjar in Iraq -- says it all.On board the helicopterCNN's Ivan Watson flies along with the Iraqi military as they drop emergency supplies.Who are the Yazidis?Why do the militant Islamists have the Yazidis in their cross hairs?Photos: Iraq under siegeImages illustrate the ongoing violence in Iraq. Will al-Maliki go without a fight?The message from a growing number of actors inside and outside Iraq is the same: Maliki must go if the country is to be saved.How ISIS recruits young menISIS gives young men "cars to drive, guns, cell phones and cash money." Survivor recalls horror of evading ISISWhich is worse: Running desperately for your life, or seeing others' lives end without enough to eat or drink?Mystical importance of Mt. SinjarThe Sinjar Mountains have always been a special place of refuge for the Yazidis.Could ISIS retaliate against West?Will the U.S. air strikes increase the terrorist threat in the U.S. and Europe?Who is ISIS targeting?Which religious and ethnic groups are under threat from ISIS militants?How to understand the Iraq crisisISIS has spread from Syria into Iraq. Learn where the militant strongholds are.Iraq's orphans left to ask: 'Why?''Why do these people kill other people?" For Iraq's youngest residents, the tragedy is almost incomprehensible.Signs of war: Life amid Iraqi conflictEven those who aren't in the line of fire feel the effects of the chaos that has engulfed Iraq since extremists attacked.More from middleeastISIS launches attack on Iraqi city of KirkukHow ISIS' new hostage strategy is shifting the goalpostsWho is Jordanian pilot Moaz al-Kassasbeh, captured by ISIS?