Story highlights The U.N. declares its highest level of emergency 
 
 U.S. military assessment determines far fewer Yazidis trapped than feared 
 
 100 Yazidi women and children are being held captive, ISIS commander tells CNN 
 
 ''I can confirm those women and children have entered Mosul,'' ISIS commander says 
 
 A mass evacuation of Yazidis hiding from extremist fighters on Iraq's Sinjar Mountains is unlikely following an assessment by the U.S. State Department and military that found far fewer people trapped than previously feared. 
 
 Once believed to be in the tens of thousands, the number of Yazidis in the mountains is "now in the low thousands," Brett McGurk, a deputy assistant secretary of state, told CNN on Wednesday. 
 
 The news broke the same day a senior commander with the Islamic State, formerly known as the Islamic State in Iraq and Syria, claimed ISIS fighters abducted more than 100 Yazidi women and children from Sinjar. 
 
 The ISIS commander, who has knowledge of the events that unfolded, said the fighters killed a large number of men when they took over the town more than a week ago. 
 
 "At that time, they took Yazidi women and children, and I can confirm those women and children have entered Mosul," the commander said by telephone. "...The Islamic State is taking this opportunity to call them to Islam." 
 
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 Photos: Iraqi refugees fleeing ISIS Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – A Yazidi family from Sinjar cleans a spot for themselves in a derelict building that houses more than a thousand other refugees on Thursday, August 14, in Zakho, Iraq. Hide Caption 1 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – A woman and child sit in the makeshift housing on Thursday. Hide Caption 2 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – A Yazidi woman holds her baby while crossing Peshkhabour bridge from Syria back into Kurdish-controlled Iraq on Tuesday, August 12. Hide Caption 3 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – Entire families carry nothing but the clothes on their back. Some are barefoot. And not everyone who set out on the arduous journey survived. Hide Caption 4 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – The militant group ISIS, which now calls itself the Islamic State, executes civilians who don't adhere to its version of Sunni Islam. Hide Caption 5 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – Yazidis fled into the barren and windswept Sinjar Mountains more than a week ago after ISIS captured their town. Hide Caption 6 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – Descendants of Kurds and followers of an ancient pre-Islamic religion, Yazidis are one of Iraq's smallest minorities, and have been persecuted for centuries, but they have a strong sense of community. Hide Caption 7 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – According to some accounts, Syrian Kurds also helped people use parts of northeastern Syria under their control to reach Kurdish areas of northern Iraq. Hide Caption 8 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – A young refugee carries a disabled man across the bridge. Hide Caption 9 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – Thousands trudge across a river to seek humanitarian aid in Syria. Hide Caption 10 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – A number of those who made the treacherous trek off the mountain told CNN that PKK fighters control parts of the mountain, and they fed and protected them from ISIS. Hide Caption 11 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – A Kurdish border guard watches while people cross. Hide Caption 12 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – A senior Kurdish official estimated that as many as 70,000 people remain trapped on Mount Sinjar, and that at least 100 have died so far from dehydration and the heat. CNN could not independently confirm those estimates. Hide Caption 13 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – A man weeps after been reunited with his family. Hide Caption 14 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – A Kurdish Peshmerga stands in front of the bridge. Hide Caption 15 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – Children rest after arriving back into Kurdish-controlled Iraq. Hide Caption 16 of 17 Photos: Iraqi refugees fleeing ISIS Iraqi refugees fleeing ISIS – A little girl was seen crossing the bridge by herself. The United States is sending more troops to northern Iraq, a move that U.S. officials told CNN is necessary to help in the rescue of tens of thousands of Yazidis trapped in the mountains. Hide Caption 17 of 17 
 
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 While CNN cannot independently confirm the claim, it follows reports by survivors who describe ISIS fighters grabbing families and separating the men from the women and children. 
 
 The plight of the Yazidis, coupled with the ISIS assault against Iraq's semiautonomous Kurdish region, prompted the United States to begin targeted airstrikes over the past several days. 
 
 The aim, according to President Barack Obama, is to help protect U.S. personnel in the area and to destroy ISIS positions around the mountains to ease the threat to minority groups. 
 
 The United States deployed 129 military advisers to get a firsthand look at the humanitarian crisis unfolding as ISIS fighters threaten Iraq's ethnic and religious minorities: Yazidis, Christians and Kurds. 
 
 As part of that effort, a group of about 20 U.S. State Department and military personnel spent 24 hours in the mountains to assess the numbers and conditions, Pentagon spokesman Rear Adm. John Kirby said. 
 
 "The Yazidis who remain are in better condition than previously believed and continue to have access to the food and water that we have dropped," he said, citing the success of humanitarian airdrops and airstrikes against ISIS. 
 
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 The problem, though, is far from over. 
 
 The United Nations on Wednesday announced its highest level of emergency for a humanitarian crisis, saying the number of people on the run from ISIS is of grave concern. 
 
 It estimates more than 400,000 people have been driven from their homes since June, when ISIS swept across the border from Syria into Iraq. 
 
 The group has waged a brutal campaign while seizing large swaths of northern and western Iraq, aiming to establish a caliphate -- an Islamic state -- that stretches from Syria to Iraq. 
 
 Of those displaced, more than 200,000 have poured into Dohuk province in recent weeks, where refugee camps have swelled since ISIS began its assault against Yazidis, Christians and Kurds. 
 
 By declaring what it calls a "Level 3 Emergency," the United Nations says it will trigger more resources to help. 
 
 Obama this week ordered the military advisers to the Kurdish capital of Irbil to assess the humanitarian crisis. 
 
 The advisers, made up of Marines and special operations forces, join hundreds of other American advisers already in the country advising Iraqi troops in their fight against ISIS, an offshoot of al Qaeda in Iraq. 
 
 The group has waged a brutal campaign while seizing large areas of territory this year in Iraq, aiming to establish a caliphate. 
 
 Adding to the crisis is Prime Minister Nuri al-Maliki's refusal to step down after Haider al-Abadi was nominated to replace him. 
 
 In a televised address on Wednesday, he called the move to appoint al-Abadi as prime minister a constitutional violation. 
 
 Al-Maliki's political party won a majority during parliamentary elections in April, but not a super majority. Even so, al-Maliki has maintained that because his party won a majority, the next Prime Minister should come from his party. 
 
 He has filed a lawsuit in federal court to stop the formation of a new government, and he has said he wouldn't step down until the court has ruled. 
 
 "We need to protect the federal court and its decisions; no one has any ground to go against this court," al-Maliki said, while not specifically mentioning the name of Prime Minister-designate al-Abadi or any other leaders. ||||| WASHINGTON — Defense Department officials said late Wednesday that United States airstrikes and Kurdish fighters had broken the Islamic militants’ siege of Mount Sinjar, allowing thousands of the Yazidis trapped there to escape. 
 
 An initial report from about a dozen Marines and Special Operations forces who arrived on Tuesday and spent 24 hours on the northern Iraqi mountain said that “the situation is much more manageable,” a senior Defense official said in an interview. 
 
 Defense Secretary Chuck Hagel, speaking to reporters Wednesday night at Andrews Air Force Base, Md., said it was “far less likely now” that the United States would undertake a rescue mission because the assessment team reported far fewer Yazidis on the mountain than expected, and that those still there were in relatively good condition. 
 
 Rear Adm. John Kirby, the Pentagon press secretary, credited American airstrikes and humanitarian airdrops as well as efforts of the Kurdish pesh merga fighters in allowing “thousands of Yazidis to evacuate from the mountain each night over the last several days” and to escape the militants from the Islamic State in Iraq and Syria. ||||| EDGARTOWN, Mass. (AP) — Crediting U.S. airstrikes and humanitarian aid, the Obama administration said Wednesday many trapped Iraqis have fled a mountain where they had sought refuge from militants, making it less likely the military would have to carry out a potentially dangerous rescue mission. 
 
 Deputy National Security Adviser for Strategic Communications and Speechwriting, Ben Rhodes, speaks during a news briefing in Edgartown, Mass., on the island of Martha's Vineyard, Wednesday, Aug. 13,... (Associated Press) 
 
 Deputy National Security Adviser for Strategic Communications and Speechwriting, Ben Rhodes, speaks during a news briefing in Edgartown, Mass., on the island of Martha's Vineyard, Wednesday, Aug. 13,... (Associated Press) 
 
 Tornados surveillance aircrafts come in to land at the British Royal Air Force Base at Akrotiri, near the southern port city of Limassol, Cyprus, on Wednesday, Aug. 13, 2014. British Bases spokesperson... (Associated Press) 
 
 The assessment came after U.S. troops secretly scouted Sinjar Mountain Wednesday, revealing far fewer people than originally thought. 
 
 Defense Secretary Chuck Hagel said six days of U.S. airstrikes against militant targets in the region gave many people an opportunity to get off the mountain. He also said the food and water supplies the U.S. airdropped to the refugees helped to sustain them during the ordeal. 
 
 U.S. officials said only several thousand refugees remained on the mountain, far lower than the tens of thousands that had been reported earlier. As a result, a rescue mission is "far less likely now," Hagel said Wednesday night, adding that those Iraqis who remained on the mountain were in relatively good condition. 
 
 President Barack Obama had been weighing a range of military options, including airlifts and humanitarian corridors, to rescue the refugees. Officials said Obama had not completely ruled out the possibility of a mission to rescue those remaining on the mountain, but agreed with Hagel's assessment that such steps were now less likely. 
 
 Obama had dispatched 129 troops to Iraq on Tuesday to assess the scope of the humanitarian crisis and options for getting the people safely off the mountain. 
 
 That process was advanced Wednesday when a team of fewer than 20 U.S. troops was flown onto the mountain by Black Hawk helicopter for a firsthand look at rescue mission possibilities. They were safely extracted hours later. 
 
 A U.S. military -led rescue mission could have involved putting American troops on the ground. The White House insisted any such action would be strictly a humanitarian rescue and would not constitute a return to combat 2 1/2 years after the last U.S. troops withdrew from Iraq. 
 
 While the U.S. has been dropping food and water to the refugees for several days, officials said they began considering a rescue mission because it was unsustainable to let thousands of people remain on the mountain. 
 
 "There needs to be a lasting solution that gets that population to a safe space where they can receive more permanent assistance," White House deputy national security adviser Ben Rhodes told reporters traveling with the president during his vacation on the Massachusetts island of Martha's Vineyard. 
 
 Thousands of Iraqi religious minorities sought refuge on Sinjar Mountain after militants from the Islamic State group swept through their village in northern Iraq. In addition to the humanitarian aid drops, the U.S. has conducted airstrikes against Islamic State targets, both to protect American personnel in the region and stop the militants from moving on the civilians again. 
 
 On Wednesday, a U.S. drone aircraft attacked and destroyed an armed truck operated by Islamic militants near Sinjar, the U.S. Central Command said. 
 
 Obama has ruled out sending combat troops back into Iraq, where nearly 4,500 Americans were killed during the eight year war that ended in 2011. 
 
 The Pentagon said the U.S. would continue to provide humanitarian assistance to the displaced Iraqis as needed, as well as take steps to protect U.S. personnel and facilities in the region. 
 
 Some of the U.S. airstrikes have been aimed at keeping militants from advancing on Irbil, the capital of the largely autonomous Iraqi Kurdish region and home to a U.S. consulate. 
 
 The Pentagon said the assessment team was transported to Irbil by a small number of V-22 Osprey aircraft from an undisclosed location in the Middle East. 
 
 The assessment team joins 90 U.S. military advisers already in Baghdad and 160 in a pair of operations centers — one in Irbil and one in Baghdad, the central government's capital — working with Iraqi security forces. 
 
 They were in addition to about 455 U.S. security forces and 100 military personnel working in the Office of Security Cooperation in the U.S. Embassy in Baghdad. 
 
 ___ 
 
 Burns reported from Washington. Associated Press writer Lolita C. Baldor at Andrews Air Force Base, Maryland, contributed to this report. 
 
 ___ 
 
 Follow Julie Pace at http://twitter.com/jpaceDC and Robert Burns at http://www.twitter.com/robertburnsAP
– It looks like the US won't have to launch a mass evacuation of Iraqis trapped on a mountain after all. A small team of American military personnel who spent 24 hours on Mount Sinjar said US airstrikes seem to have done the trick—most of the trapped Yazidis who wanted to flee to safety have done so, reports the New York Times. As a result, defense chief Chuck Hagel said a rescue mission is "far less likely now," reports the AP. Exact numbers weren't available, but CNN quotes a Pentagon spokesman as saying that "far fewer" Yazidis were on the mountain than expected. He estimated "several thousand" but said many wanted to stay there because their homes are nearby. Earlier, the US deployed 130 troops to Iraq, and President Obama said he would be willing to use those troops as part of a rescue mission.