Detailed Instructions: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Q: Image copyright AP Image caption The USS George HW Bush has been sent to the Gulf by the US along with two other military vessels 
  
 Washington is considering direct talks with Iran on the security situation in Iraq, a US official has told the BBC. 
  
 The move comes as US President Barack Obama weighs up options on action to take in Iraq. 
  
 Meanwhile, the US condemned as "horrifying" photos posted online by Sunni militants that appear to show fighters massacring Iraqi soldiers. 
  
 In the scenes, the soldiers are shown being led away and lying in trenches before and after their "execution". 
  
 The Iraqi military said the pictures were real, but their authenticity has not been independently confirmed. 
  
 The BBC's Jim Muir, in northern Iraq, says if the photographs are genuine, it would be by far the biggest single atrocity since the time of the American-led invasion of Iraq in 2003. 
  
 Their emergence came as the Iraqi government claimed to have "regained the initiative" against an offensive by Sunni rebels led by ISIS - the Islamic State in Iraq and the Levant. 
  
 Extremists captured key cities, including Mosul and Tikrit, last week, but several towns have now been retaken from the rebels. 
  
 However the insurgents captured the northern city of Tal Afar, west of Mosul, overnight after a heavy mortar bombardment. 
  
 Media playback is unsupported on your device Media caption The images appear to show captured Iraqi soldiers in civilian clothes being led away by militants, as the BBC's John Simpson reports 
  
 Vienna talks 
  
 While the US and Iran are old adversaries, both have an interest in curbing the growing threat posed by ISIS and both are considering military support to the Iraqi government, says the BBC's Rajini Vaidyanathan in Washington. 
  
 The US is said to be considering direct discussions with Tehran which could even take place as early as this week. 
  
 The two countries are due to hold the latest round of talks on Iran's nuclear programme in Vienna. 
  
 Iranian President Hassan Rouhani has said he will consider co-operation if the US takes action in Iraq. 
  
 The USS George HW Bush aircraft carrier is already being deployed to the Gulf, accompanied by two more warships. But Washington says no US troops will be deployed on the ground. 
  
 The US has also announced it is increasing security at its embassy in Baghdad and relocating some staff to safer areas. 
  
 Meanwhile, there are reports that more than 130 Iranian Revolutionary Guards are in Iraq to provide training and advice. 
  
 Image copyright AP Image caption The pictures have not been independently verified, but military sources said they were authentic 
  
 Taken in trucks 
  
 The massacre pictures, apparently posted by ISIS, are said to show what happened to soldiers after the group took over an army base in Tikrit. 
  
 Video footage, apparently filmed earlier, shows many hundreds of men being marched off, with the voice on tape saying they had surrendered at the Speicher base. 
  
 Still photographs show large numbers of young men being transported away in trucks. 
  
 Captions on the photographs, which again appeared to have been issued by ISIS, said they were being taken away to their deaths. 
  
 What appear to be ISIS fighters are seen firing on their captives in some images. 
  
 Media playback is unsupported on your device Media caption The insurgency is increasingly splitting communities along sectarian lines, as the BBC's Paul Wood reports 
  
 Sources in the rebel movement, who do not belong to ISIS, told the BBC they believed as many as 1,000 personnel from the base had been executed. 
  
 They said the ISIS fighters had divided them into regular army conscripts, who were set free, and volunteers from Shia militias or from the government's elite Golden Brigade, who were condemned to die. 
  
 Earlier, Iraqi army spokesman Lt Gen Qasim Ata said the military had scored successes against the militants in several areas, killing 279 of them. The figure could not be independently verified. 
  
 Government forces were reported to be building up in the city of Samarra, north of Baghdad, ready for a counter-offensive on Tikrit. 
  
 Image copyright AP Image caption There are reports that thousands of men have joined Shia militias 
  
 ISIS in Iraq 
  
 The Islamic State in Iraq and the Levant (ISIS) has 3,000 to 5,000 fighters, and grew out of an al-Qaeda-linked organisation in Iraq 
  
 Joined in its offensives by other Sunni militant groups, including Saddam-era officers and soldiers, and disaffected Sunni tribal fighters 
  
 ISIS has exploited the standoff between the Iraqi government and the minority Sunni Arab community, which complains that Shia Prime Minister Nouri Maliki is monopolising power 
  
 The organisation is led by Abu Bakr al-Baghdadi, an obscure figure regarded as a battlefield commander and tactician 
  
 Are you in Saadiya, Jalawla or Baghdad? Have you been affected by the latest developments? You can email haveyoursay@bbc.co.uk using the title 'Iraq'. ||||| 11.30pm BST 
  
 We're going to wrap up our live blog coverage for the day. Here's a summary of where things stand: 
  
 • Isis fighters and allied groups took new territory in northern and western Iraq, including the city of Tal Afar, along a main route into Syria. 
  
 • Isis claims that it had killed 1,700 Iraqi soldiers were questioned. But videos of Isis executions of Iraqi security forces stirred outrage. Some diagnosed a broader sectarian conflict to come. 
  
  
  
 • Forces in Iraq engaged Isis and prepared for a larger confrontation. These included the Iraqi army, Kurdish peshmerga, Shia militias, Iranian fighters, volunteers and security forces. 
  
 • Iranian and US officials discussed the Iraq situation on the sidelines of nuclear talks in Vienna. Both sides ruled out military cooperation, although US secretary of state John Kerry earlier in the day left the option open. 
  
 • Kerry also said US air strikes in Iraq were an option. President Obama and national security advisors planned to meet Monday evening on Iraq. 
  
 • An Iraqi army helicopter was reportedly shot down during clashes with militants west of Baghdad. 
  
 • Hundreds of thousands of Iraqis were unable to return to their homes after they fled the Isis advance last week. A few of their stories are here and here. ||||| GENEVA (AP) — Reports of Islamic militants massacring scores of captured Iraqi soldiers are "deeply disturbing" and those responsible for it must be brought to justice, U.N. Secretary-General Ban Ki-moon said Monday. 
  
 The U.N. chief warned against sectarian rhetoric in Iraq that could inflame the conflict and carry grave implications for the entire region. 
  
 He said he welcomed the statement on the need for unity in Iraq made by Grand Ayatollah Sayed Ali Al-Sistani, who he said "represents a deeply influential voice of wisdom and reason." 
  
 The Islamic militants who overran cities and towns in Iraq last week have posted graphic photos on a militant website that appear to show masked fighters of the Islamic State of Iraq and the Levant, or ISIL, loading the captives onto flatbed trucks before forcing them to lie face-down in a shallow ditch with their arms tied behind their backs. The final images show the bodies of the captives soaked in blood after being shot at several locations. 
  
 Iraq's chief military spokesman, Lt. Gen. Qassim al-Moussawi, confirmed the photos' authenticity Sunday and said he was aware of cases of mass murder of captured Iraqi soldiers in areas held by ISIL. 
  
 "Reports of mass summary executions by ISIL are deeply disturbing and underscore the urgency of bringing the perpetrators of such crimes to justice," Ban said. 
  
 He also called on all Iraqi leaders across the spectrum of political, military, religious and community posts to ensure that their followers avoid acts of reprisal. 
  
 Ban urged the international community to unite in showing solidarity with Iraq as it confronts "this serious security challenge" and called for full respect for international humanitarian law and human rights law in efforts to counter terrorism and violence in Iraq. 
  
 U.N. human rights chief Navi Pillay warned Friday against "murder of all kinds" and other war crimes in Iraq, saying the number killed in recent days may run into the hundreds. |||||
A:
Militants from the Islamic State of Iraq and Syria say they've slaughtered 1,700 Iraqi soldiers in Tikrit, a massacre that, if confirmed, would be by far the largest atrocity in the country in more than a decade. The militants released photos late Saturday showing the soldiers being led to trenches and then face-down in them before and after their execution. Sources tell the BBC that captured soldiers were divided into ordinary conscripts, who were freed, and volunteers from Shia militias, who were massacred. But some Iraqi officials and human rights groups are casting doubt on the number of dead, the New York Times reports. "I would have thought there would have been leverage in keeping those prisoners alive," a Guardian correspondent says. "My suspicion is that they remain alive but in desperate peril." The photos, uploaded to an ISIS Twitter account, show what could be as many as seven massacre sites, though the Times notes they could also be various angles of fewer sites. No individual photo depicts more than 60 victims. The captions are particularly inflammatory, notes the Times. A sampling: "The filthy Shiites are killed in the hundreds," and "The liquidation of the Shiites who ran away from their military bases." The US decried the photos as "horrible." Washington is so unsettled by the conflict that it is considering direct talks with frequent rival Iran to resolve it. Those talks could come as early as this week, during scheduled nuclear negotiations in Vienna. The UN called the reports "deeply disturbing," the AP reports. The photos and their captions seemed designed to incite sectarian violence, and Ban-Ki Moon praised Ayatollah Ali al-Sistani for calling for "the highest possible level of self-restraint. Militants have also taken yet another city, seizing Tal Afar, which is west of Musl, after two days of fighting, senior Iraqi security officials tell the Times. According to Iraqi state TV, Iraq's military is beginning to strike back after losing cities across the country in last week's stunning rebel advance, CNN reports. State TV says hundreds of militants were killed in airstrikes near Fallujah. Government forces are also believed to be gathering near Samarra in preparation for an attempt to retake Tikrit.