The United States on Saturday expressed "deep concern over the destabilizing activities" of the Iranian Revolutionary Guards and Hizbullah in Iraq and throughout the region. The comment made by the US Embassy in Tel Aviv to The Jerusalem Post came after it was revealed by the American military that Iraqi Shi'ite assassination teams are being trained in at least four locations in Iran by the Quds force (a branch of Iran's Revolutionary Guard) and Hizbullah. According to intelligence gleaned from captured militiamen and other sources in Iraq, the Shi'ite death squads are planning to return to Iraq in the next few months to kill specific Iraqi officials as well as US and Iraqi troops. US Embassy officials said the Quds force was the primary executor of Iran's policies in Iraq, and had supplied Iraqi Shi'ites with small arms, mortars, battlefield rockets and explosives that had been used in attacks on coalition forces and Iraqi government leaders. In late 2007, a series of detentions by coalition forces of Shi'ite gunmen led to information that Mahdi Army Special Group members were being sent to Iran for training in guerrilla warfare. The Quds Force enlisted the help of its long-standing partner, Hizbullah, to train and support the Special Groups, the officials said. The Quds Force is the Iranian regime's primary mechanism for cultivating and supporting Islamic terrorists abroad, including Hizbullah, Palestinian organizations, certain Iraqi Shi'ite groups, and Islamic gunmen in Afghanistan, the Balkans and elsewhere. A senior US military intelligence officer in Baghdad detailed the information on Thursday in an interview with The Associated Press. The officer provided Iraq's national security adviser with several lists of the assassination teams' expected targets on Wednesday. He said the targets included many judges but would not otherwise identify them. Iraq's intelligence service is preparing operations to determine where and when the special group gunmen will enter the country and is to provide an assessment to Prime Minister Nouri al-Maliki. The US official acknowledged disclosing the information in an attempt to pressure Iran to suspend the training and prevent the militiamen from returning to Iraq. The US military also wants the Iraqi government to take steps to protect the targets. Wanted posters picturing men believed to be heading the special groups are being posted around Baghdad, the military officer said. The US also is encouraging the Iraqi government to confront Iran with the information in diplomatic channels, and it wants Iraq to continue pumping money into its own reconstruction. By building stability and Iraqis' confidence in their government, internal support for militia groups should decline, making it more difficult for them to operate. The would-be assassins are expected to return to Iraq between now and October, but the officer said there was no intelligence suggesting they were actually in Iraq yet. Many of the gunmen fled to Iran earlier this year after Iraqi government forces cracked down first on militia sanctuaries in Basra and Baghdad's Sadr City district, then in Amarah and now in Diyala province, the military officer said. One of the reasons the US believes the special groups moved out during that period is the sharp decline in deadly roadside bombs bearing Iran's signature explosive design. In March, there were 55 such attacks. By July, that number had dropped to around 18, the officer said. US intelligence believes those sophisticated bombs can be traced back to Iran. Iran denies giving any support to Shi'ite extremists in Iraq. The officer said training was going on in at least four locations in Iran: Qom, Teheran, Ahvaz and Mashhad. The number of "special group criminals" - the US name for Iraqi fighters sponsored by Iran - is unknown but is estimated in the hundreds and possibly more than 1,000. According to the officer, the training camps are operating under the direction of Quds force commander Brig.-Gen. Ghassem Soleimani, with the knowledge and approval of Iran's supreme leader, Ayatollah Ali Khamenei. The training includes how to conduct reconnaissance to pinpoint targets, small arms and weapons training, small unit tactics and terrorist cell operations and communications. They are also learning how to use bombs packed with explosive penetrators that can rip through US armored vehicles, along with other improvised explosive devices and rocket-propelled grenades, including the RPG-29 used by Hizbullah and the Quds force. They are also receiving training on assassination techniques, employing rocket-propelled grenades, small arms or explosives, the officer said. Hizbullah conducts much of the training in the camps because they speak Arabic. Hizbullah also has credibility with the Iraqis, given their success in the Second Lebanon War in 2006, the officer said. The US officer said there are no confirmed reports of Hizbullah members crossing into Iraq in recent months. That conflicts with what Iraqi Shi'ite lawmakers and a top Iraqi army officer told the AP last month: Hizbullah trainers were running training camps in southern Iraq until April, when they were pushed into Iran by the Iraqi crackdown. The trainees in the Iranian camps include three Iraqis already wanted by the Iraqi government for terrorist attacks: Haji Mahdi, Haji Thamir and Baqir al-Sa'idi, the officer said. He identified two Iraqi Shi'ite militia groups in Iran by name: "The League of the Righteous," or "Asaib al-Haq," and the "Kataib al-Hizbullah." Foot soldiers and cell leaders were physically separated for most of the training, the officer said. Leaders were trained in Teheran and cell members were in separate camps where Quds trainers attempt to indoctrinate them without competition from their Iraqi leaders. The "special group criminals" are offshoots of cleric Muqtada al-Sadr's Mahdi Army militia. They spun off their own groups after Sadr declared a cease-fire with the Iraqi government in August 2007 and are not thought to be under his control now.