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. ||||| Displaced families from the minority Yazidi sect fled the violence in the Iraqi town of Sinjar, just west of Mosul, and took refuge at Dohuk province on Aug. 4. (Ari Jala/Reuters) 
 
 Politicians appealed Wednesday for emergency aid for thousands of minority Iraqis who have been stranded with little food on a mountaintop in the country’s northwest, surrounded by al-Qaeda-inspired rebels. 
 
 For nearly two months, Kurdish forces had managed to protect the area from the Sunni extremists who have rampaged through much of northern Iraq, slaughtering opponents, destroying ancient shrines and demanding that people of other religions convert or die. But last weekend the famously tough Kurdish fighters suffered their first setbacks in the Sinjar region, prompting hundreds of thousands of civilians to flee. 
 
 An estimated 10,000 to 40,000 of them sought refuge on the craggy peaks of Mount Sinjar — largely members of the minority Yazidi sect. They fear death if they descend into areas controlled by the extremist rebels, who consider them apostates. Kurdish forces have so far failed to break through the militants’ lines to reach them, despite launching a counteroffensive early this week. 
 
 The Iraqi government conducted two airdrops of aid to the desperate refugees on Wednesday, but humanitarian workers said they did not come close to meeting the growing need. Some of the water bottles in the aid bundles cracked open. 
 
 “Is help coming?” one of those trapped on the mountain, 23-year-old Shihab Balki, asked when contacted by cellphone — one of the few belonging to the refugees that still had battery life. He said that at least 17 children have died on the mountain because of the inhospitable conditions. 
 
 Iraqi politician Vian Dakhil makes a raw, emotional plea for the protection of the Yazidi people before Iraqi parliament. (YouTube/Al Sumaria TV) 
 
 “I’m standing here next to an old lady and a child lying on the ground. They are not dead, but we fear they are dying,” Balki said. 
 
 UNICEF says it has confirmed that children have perished on Mount Sinjar but does not have verified up-to-date figures. 
 
 Balki said later Wednesday that he had managed to secure about four gallons of water for his family of seven from one of the day’s airdrops — not nearly enough in the hot Iraqi summer. Many of the bottles dropped in a wooden crate had cracked, their precious contents spilling onto the rocks, he said. Earlier airdrops included food and milk, but the cartons of milk also smashed on the mountainside, he said. 
 
 Haji Ghandour, a Yazidi member of parliament in Baghdad, said the shortage of aid was acute. 
 
 “There are some airdrops, but they aren’t even covering half the need,” he said. “Most of these supplies fall near to [Islamic State fighters], others break and are ruined. The operation is not accurate.” 
 
 The United Nations says the Iraqi government has yet to take up an offer of technical assistance for airdrops, which are being coordinated with local authorities in the semiautonomous Kurdish region in northeastern Iraq. 
 
 Falah Mustafa Bakir, the Kurdistan region’s foreign minister, argued that Iraq simply lacks the capacity to provide aid and needs international help. “This is not a time for technical assistance,” he said. “This is a time for immediate action. Children are dying.” 
 
 Displaced families from the minority Yazidi sect take refuge Aug. 4 in Dohuk province. Prime Minister Nouri al-Maliki has ordered his air force to back Kurdish forces against Islamic State fighters. (Ari Jala/Reuters) 
 
 In Washington, Obama administration officials did not respond Wednesday to queries about whether the U.S. government was considering providing assistance. 
 
 Trouble on several fronts 
 
 Meanwhile, tens of thousands of newly displaced people have flooded into the Kurdish region, which Bakir said lacks the finances to assist them. The region, which is home to just over 5 million residents, is now hosting an additional 1.5 million people — refugees from the Syrian war and internally displaced Iraqis, he said. 
 
 Kurdish officials had warned for weeks that they were unable to maintain the fight along the semiautonomous region’s 650-mile-long front with the militants, unless the Kurds got outside support. A lack of ammunition and advanced weaponry forced the retreat from Sinjar, Kurdish officials say. 
 
 The Kurds say they are trying to put out fires on multiple fronts, trying to recapture land only to be attacked elsewhere as the Islamic State continues to jab at its boundaries. 
 
 That threat was underscored on Wednesday when, as Kurdish forces continued their counter­offensive near Sinjar, they were forced to send reinforcements 150 miles east to Makhmur and Gweir as militants attempted to push closer to their regional capital, Irbil. 
 
 “It’s not fair that we are left fighting these terrorists alone,” said Bakir, the Kurdistan region’s foreign minister. “We need immediate action. We look to the United States, we look to NATO.” 
 
 “The West have armed many groups around the world. Why not help us be in the front against terrorism?” Bakir said. “We don’t understand.” 
 
 Kurds receive air cover 
 
 The Kurds are supposed to receive a share of weapons and budgetary outlays from the national government in Baghdad. But relations between the two governments have soured, as some prominent Kurdish leaders have called for independence. 
 
 In recent days, however, the Iraqi military has started providing air cover to Kurdish security forces known as pesh merga. 
 
 Still, Kurdish troops have not been paid for months because of the suspension of budget payments from Baghdad, and the northern region has struggled to procure military supplies. Those relations are likely to worsen if Iraqi Prime Minister Nouri al-Maliki stays in power, with a change in leadership seen by many as the only way of keeping the north from splitting away. Maliki has held the country’s top political job since 2006. 
 
 Maliki appeared defiant on Wednesday, even though the country’s religious authorities and his own party are indicating he should step aside. He argued that his political bloc had won the largest share in the elections in April and should be allowed to nominate the prime minister. 
 
 If the constitution is ignored, it will “open the gates of hell” in Iraq, he said. 
 
 Mustafa Salim in Baghdad and Karen DeYoung in Washington contributed to this report.
– Another 130 Marines and special operations forces have been sent to Iraq to help rescue tens of thousands of Yazidi refugees still trapped on a mountain, but this "is not a combat boots on the ground kind of operation," Defense Secretary Chuck Hagel says. Speaking at California's Camp Pendleton, he described the extra American troops now in the northern city of Irbil as "assessment team members" who will assist the effort to help members of the Yazidi minority threatened by Islamic State extremists. A helicopter bringing supplies to people trapped on Mount Sinjar crashed yesterday after too many refugees climbed on board. More: As the plight of the refugees becomes increasingly desperate, American officials say a ground force may be necessary to get the refugees off the mountain, the New York Times reports. John Kerry says the 130 advisers will be tasked with finding a safe way out. "We will make a very rapid and critical assessment because we understand it is urgent to try to move those people off the mountain," he told reporters today. Prime Minister Nouri al-Maliki, meanwhile, appears to have given up on trying to cling to power at any cost, the New York Times notes. He has told troops deployed in Baghdad not to intervene in the crisis—and officials say the military has told Maliki he no longer has their support. Insiders say discussions on Maliki stepping down are now focused on immunity from prosecution. New Iraqi President Fouad Massoum has chosen deputy parliament speaker Haider al-Ibadi as Maliki's replacement. France is sending arms in "coming hours" to Kurds fighting the Islamic State in a situation it calls "catastrophic," reports the AP. The move comes with Baghdad's blessing. Across the border in Syria, Islamic State militants have made fresh gains, reports the AP. Opposition activists say fighters have seized two key towns near the Turkish border after clashes with other rebel groups.