Iraq Terror Group Posts Tape of Killings By BRIAN MURPHY, Associated Press Writer BAGHDAD, Iraq - An al-Qaida-affiliated group said Saturday it killed 18 kidnapped government security forces in retaliation for the alleged rape of a Sunni woman by members of the Shiite-dominated police, posting an online video of the officers being shot in the back of their heads while kneeling in a field. The authenticity of the three-minute video, posted on a Web site previously used by the Islamic State of Iraq, could not be immediately verified. The group also said it had killed 14 policemen, whose bodies were found Friday in the northeast province of Diyala, in retaliation for the alleged rape. Some of the victims were decapitated, according to an Associated Press photographer. Meanwhile, gunmen rounded up two Sunni families that had received death threats for joining U.S.-organized talks with local Shiites, hauling away the men and boys and killing all six Saturday as suspected insurgents expanded a campaign of fear against opponents. U.S. forces also reported airstrikes and raids on what it called Sunni militant bases linked to al-Qaida in Iraq. A recent wave of Sunni reprisals appears linked to increasingly high-profile attempts to stir popular momentum against Sunni extremists trying to drive out the Shiite-led government and its American backers. Among those targeted include a range of Sunnis raising their voices against violence: imams, clan-based vigilantes and activists trying to bridge deep rifts with majority Shiites. The execution video released Saturday first depicts the 18 men, some in Iraqi military uniforms, blindfolded, hands tied behind their backs and lined up in three rows before a screen. The men in the front row are kneeling. Armed masked men were seen pointing machine guns at the captives. Two masked militants, with checkered scarves on their heads, then fire from handguns at close range into the backs of the men's heads, while a third militant carries a black banner ahead of them. As they are shot, the victims fall, head forward to the ground. The shooting is accompanied by chants of "Allahu Akbar," or "God is the Greatest." Male voices chant repeatedly in Arabic during the video: "At your service, sister" _ a likely reference to the revenge for the allegedly raped Sunni woman. Another male voice is heard reading from the Islamic State of Iraq's statement posted on the same Web site Friday, saying the group's court had ordered the 18 security troops executed because Prime Minister Nouri al-Maliki's government had failed to meet the group's demands to hand over the officers who allegedly assaulted the Sunni woman in Baghdad last month, and to release all Sunni women detainees from Iraqi prisons. A 20-year-old woman told Arab television stations that she was detained in a Sunni area of west Baghdad on Feb. 18, taken to a police garrison and assaulted by three officers. The woman gave a name which identified her as Sunni. Al-Maliki, a Shiite, announced an investigation Feb. 19 but cleared the officers the following day, stirring outrage among Sunni politicians. Al-Maliki said the rape claim was fabricated to tarnish the reputation of the police and the security crackdown in Baghdad. The two families gunned down at sunrise Saturday had received death threats for weeks after attending gatherings of Sunni and Shiite leaders, police said. The first meeting, organized by U.S. military officials on Feb. 13, brought together leaders of prominent clans from both sides, said military spokesman Maj. Webster M. Wright III. The clan chiefs held another round on their own about a week later and appointed a joint council "to discuss the terms of reconciliation" around Youssifiyah, a Sunni-dominated area about 12 miles south of Baghdad, Wright said. At dawn, gunmen stormed the home of two families belonging to the influential Sunni Mashhada tribe, said police 1st Lt. Haider Satar. Two fathers and their four sons were separated from their wives and sisters. They were executed at point-blank range. In the morgue in nearby Mahmoudiya, AP Television News footage showed at least two victims had their hands bound behind their backs. Al-Maliki is under strong pressure from Washington to take a stronger hand against Sunni insurgents and the Shiite militia that forms part of his power base. In an interview with the AP, he said he will reshuffle his 39-seat Cabinet "either this week or next" and pursue criminal charges against political figures _ and even members of parliament _ linked to extremists. He said there has been coordination between Iraqi and multinational forces from the beginning of the year "to determine who should arrested and the reasons behind arresting them." The prime minister did not say how many Cabinet members would be replaced. But some officials said about nine would lose their jobs, including all six Cabinet members loyal to radical anti-American Shiite cleric Muqtada al-Sadr, who leads the powerful Mahdi Army militia. U.S. officials had been urging al-Maliki to cut his ties to al-Sadr and form a new alliance of mainstream Shiites, moderate Sunnis and Kurds. Al-Maliki has won some breathing room in recent days with a notable _ but perhaps temporary _ drop in bloodshed in Baghdad. It comes as a U.S.-led security crackdown concentrates on areas considered staging grounds for Sunni insurgent car bombs and mortar attacks. The Mahdi Army also was strong-armed by al-Maliki to pull back. Its suspected death squads once left dozens of Sunni victims around the city _ a figure that has fallen off significantly. For the second consecutive day, just one major explosion rocked the capital. The latest _ a roadside bomb _ killed three U.S. soldiers on patrol in central Baghdad, the military said. In western Baghdad, meanwhile, a top adviser to Iraq's Defense Ministry was kidnapped in western Baghdad, said an aide to Adnan al-Dulaimi, a leader of the largest Sunni bloc in parliament. Lt. Gen. Thamir Sultan hails from Saddam Hussein's tribe and had been mentioned as a possible defense minister when the current government was organized last year. The aide spoke on condition of anonymity because he was not authorized to release the information. In U.S. raids north of Baghdad, nine suspected insurgents were captured, including two believed to be responsible for recruiting and helping foreign militants in Baghdad, the U.S. military said. The suspects were also accused of harboring al-Qaida in Iraq leaders, it said, but gave no further details. U.S. warplanes also struck a suspected car bomb factory in Arab Jabour, south of Baghdad, the military said. Seven suspected insurgents were killed when two precision-guided bombs destroyed the structure where they were hiding, the military said.