US troops in Iraq have been targeted three times in mortars and katyusha rocket strikes since last weekend. The attacks have occurred in the middle of rising tensions between the United States and Iran. While no group has claimed credit for the incidents, Shia militias that are supported by Iran are suspected of carrying them out.

On Saturday, several mortars were fired at the Balad Air Base, which hosts American trainers in central Iraq. Iraqi officials stated that the mortars did not cause any damage, nor were any Iraqi or American personnel reported injured.

Two days later, three katyusha rockets were fired into Camp Taji, just north of Baghdad. Like the Balad Air Base, Camp Taji also hosts American personnel. No damage or injuries were reported in the rocket strikes.

Today, another katyusha rocket, reportedly locally-made, was fired into the joint US-Iraqi base at the presidential palace complex in Mosul. No damage or injuries were reported.

Last month, it was widely suspected that Iranian-backed militants also fired a katyusha rocket at the US embassy in Baghdad’s Green Zone. Another katyusha strike directed at Camp Taji was also reportedly thwarted by Iraqi forces last month.

In all four cases, no claims of responsibility have been issued. However, it is widely suspected that Iranian-supported militias, which are part of Iraq’s Popular Mobilization Units (PMU) are responsible. The areas in which the attacks have occurred are areas with a strong PMU presence.

Iran has created and supported a number of Shia militias in Iraq to increase its influence in the country, counter the US presence in Iraq and the region, as well as serve as proxies in the Syria civil war. These militias are responsible for killing over 600 troops during and after the surge as the US battle al Qaeda in Iraq.

The PMU is dominated by Shia militias that are backed by Iran and its Islamic Revolutionary Guards Corps (IRGC). It is led by Abu Mahdi al Muhandis, who is listed by the US as a Specially Designated Global Terrorist and also the leader of the Hezbollah Brigades, and Hader al Amiri, the head of the Badr Organization. Both Muhandis and Amiri are closely tied to the IRGC and Iran. Hezbollah Brigades is listed by the US as a terrorist entity.

The PMU directly reports to Iraq’s prime minister and does not fall under the command of the Ministries of Interior or Defense. In July 2016, the PMU was officially incorporated into Iraq’s security forces. The unit acts much like Iran’s IRGC, and prominent PMU leaders have said they would obey Iran’s Supreme Leader if he ordered them to overthrow the Iraqi government.

The recent strikes in Iraq take place as tensions between the United States and Iran have escalated following attacks on oil tankers in the Gulf of Oman. The US has fingered Iran as the culprit, a claim Iran denies. US Central Command (CENTOM) said the last two attacks, which took place in the Gulf of Oman on June 13, were carried out by the IRGC. An IRGC patrol boat was “observed and recorded removing the unexploded limpet mine” from one of the tankers.

Additionally, CENTCOM reported that the IRGC fired a surface-to-air missile at a US MQ-9 Reaper as it was observing one of the vessels involved in the June 13 attacks in the Gulf of Oman. Also, on June 6, Houthi rebels in Yemen, which are backed by the IRGC, shot down a Reaper. That shoot down “was enabled by Iranian assistance,” CENTCOM reported.

Bill Roggio is a Senior Fellow at the Foundation for Defense of Democracies and the Editor of The Long War Journal. Caleb Weiss is an intern at the Foundation for Defense of Democracies and a contributor to The Long War Journal.

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