Forty-eight tense hours separated an attack that killed a U.S. contractor at a base near Kirkuk on Friday, December 27, and U.S. attacks against the Kataib Hezbollah militia in Iraq and Syria on Sunday. It is a serious response that backs up six months of Washington’s rhetoric which has warned Iran of a strong and decisive response to any attacks by Tehran or its proxies. 

The United States opened a new chapter in Iraq on Sunday with its airstrikes. The strikes, carried out by F-15s and other aircraft, hit five targets, three in Iraq and two in Syria. The largest strike hit a headquarters of Kataib Hezbollah in Al-Qaim and killed several members of the militia. According to local reports Abu Al-Khazali, a commander of Brigade 45 of the Popular Mobilization Units (PMU), was killed. Brigade 45 is made up of Kataib Hezbollah members and is officially a paramilitary unit within the Iraqi Security Forces.

The airstrike is a response to rocket fire that killed a U.S. contractor and wounded four U.S. personnel at the K-1 base northwest of Kirkuk. It was the latest of at least ten attacks since October 2019. These attacks actually began earlier this year when rockets were aimed at U.S. bases in February and May. When U.S.-Iran tensions skyrocketed in May the attacks increased. In May, Secretary of State Mike Pompeo flew to Iraq to warn of Iranian attacks. The attacks did come, but in the form of mining oil tankers in the Gulf and then the downing of a U.S. drone in June. Then Iran shifted tactics a bit, targeting Saudi Arabia’s Abqaiq facility and also targeting Israel. There were Iranian rocket attacks on Israel in May of 2018 and in January, September and November this year.

Iran’s strategy is complex. In Iraq, Syria, Lebanon and Yemen it works with local forces. These include Hezbollah, the Houthi rebels and Shia militias, many of them linked to the Islamic Revolutionary Guard Corps. Pompeo calls these “proxies” and warned on December 13 that Iran’s proxies had “recently conducted several attacks against bases where Iraqi Security Forces are co-located [with] US and international coalition personnel.” The United States and Coalition are in Iraq with thousands of forces to fight ISIS. The United States had reduced its diplomatic staff in Iraq due to the Iran tensions. Protests in Iraq that began in October led to the resignation of Prime Minister Adel Abdul Mahdi and the country has a leadership vacuum. President Barham Saleh, who met with Pompeo at the sidelines of the UN in September, has threatened to resign.

The U.S. role in Iraq has become increasingly complicated well. With ISIS largely defeated in Iraq in the fall of 2017, the United States shifted to stabilization, training and dispatching Security Force Assistance Brigades—in an advisory role—to advise the Iraqis and Kurdish Peshmerga. The Coalition highlights weekly raids against ISIS and the United States conducts some airstrikes. However, Lead Inspector General reports show that tensions with Iran are increasingly on the minds of U.S. forces.

The Iran tensions span Iraq and Syria. This is partly a result of the war against ISIS which spanned across both countries. Similarly, pro-Iranian groups in Syria and Iraq also fought ISIS and filled the vacuum left behind. In Iraq, that meant that the Popular Mobilization Units, a group of mostly Shia militias, set up bases in places like Kirkuk, Nineveh and Anbar province. In Al-Qaim, for instance, the 45^th Brigade of the PMU, linked to Kataib Hezbollah, set up a base. It also built a base on the Syrian side in a house. Iran also built a base on the Syrian side near Albukamal called the Imam Ali base. Together Kataib Hezbollah units and the Imam Ali base have been hit by Israeli airstrikes.

For the United States, the concern in Iraq and Syria is multi-layered. After the U.S. withdrawal from part of northern Syria, it repositioned units to guard oil and keep a presence in southern Syria. It has warned the Syrian regime against advancing into these areas east of the Euphrates or around the Tanf base on the Jordanian base. In February 2018, the United States helped stop a Syrian regime advance near Deir Ezzor that included Russian mercenaries.

In Syria, the United States has expressed concern that Israeli airstrikes might lead the Syrian regime or its allies to target the United States. In Iraq, the United States says Israeli airstrikes have complicated the mission a bit. Israel has said it opposes Iranian entrenchment in Syria and Iraq. In a sense, the United States and Israel view Iran’s threats similarly, but they have different challenges. Israel wants Iran to stop moving munitions to Syria and reduce its presence. The United States wants to be able to continue the anti-ISIS campaign without Iranian-backed harassment. But Iran has shown that it will conduct tit-for-tat pressures in response to sanctions and other issues. Iranian-backed groups, such as Kataib Hezbollah and Asaib Ahl al-Haq (AAH) have a long history of opposing and fighting the United States in Iraq, only stopping momentarily due to the war against ISIS. The United States sanctioned Kataib Hezbollah leader Abu Mahdi al-Muhandis in 2009 and he is wanted for terrorism charges in Kuwait. Washington also sanctioned Qais Khazali, leader of AAH, in December and has sanctioned Harakat Hezbollah Al-Nujaba, another PMU militia.

All this adds up to a very tense December, even without the attack and retaliation that just took place. PMU militia leaders like Muhandis want the United States to leave Iraq. The Pentagon says that Kataib Hezbollah has been responsible for past rocket attacks on bases where U.S. forces are present. These attacks have become increasingly threatening since October; they have included different types of rockets, including Iranian-made 107mm rockets. On December 27, a total of thirty-two rockets fired from an improvised rocket launcher in the back of a Bongo truck, struck the K-1 base. U.S. personnel were there as part of an anti-ISIS operation. The rockets set off a munitions facility. One U.S. contractor was killed.

On December 29, the F-15s dropped their ordnance in Iraq and Syria. The Pentagon says that targets included command and control areas and also storage facilities that Kataib Hezbollah has used to plan and execute attacks on the U.S. and coalition forces. The decision to strike in both Syria and Iraq shows that Washington views the threat as spanning the border. It is highly unusual for the United States to conduct airstrikes this way, across borders at the same threat. The only parallel might be the conflict against groups like Al-Qaeda that have spanned continents and resulted in U.S. drone strikes, many of them confidential, from Pakistan to Africa.

The strikes represent a keen understanding of the threat that Kataib Hezbollah poses. It is not just an Iraqi militia: its leader trained with the IRGC in the 1980s and it is part of Iran’s regional strategy. In that sense, like AAH and other groups in Iraq, it has played a role in Syria, established relations with Hezbollah, and has threatened Israel. Like the rest of Iran’s proxies, it views itself as “resisting” the United States in the Middle East.

The Trump administration has been reticent to get involved in a conflict with Iran despite the rising tensions since May. However, the Trump administration has tested Iran’s role in Iraq in the past. In October 2017, former Secretary of State Rex Tillerson said that the Iraqi militias, such as Kataib Hezbollah, should go home now that the war on ISIS was over. Then-Prime Minister Haider al-Abadi condemned Tillerson and said the militias of the PMU were the hope of the future of Iraq and the region. In December 2018, President Donald Trump said the United States could use Iraq to “watch Iran.” Similar statements in January 2019 ruffled Iran’s feathers and angered Iraqi politicians who didn’t want Iraq used as part of a U.S. war with Iran. Hadi al-Amiri, head of the Badr Organization, which is part of the PMU, warned in May that tensions with the United States and Iran could “burn” Iraq.

The tensions point to a crucial moment for the United States in Iraq. Washington has already left Iraq several times in the past: In the 1990s, after the Gulf War US forces withdrew and again in 2011. Now pro-Iranian groups want to see the United States leave again. Iraqis don’t want a U.S.-Iran conflict or a proxy conflict in Iraq. But many Iraqi protesters have been protesting Iran’s presence as well, not only the U.S. presence. Iranian consulates have been burned, militia headquarters have been targeted, and Iranian-backed militias have been accused of killing protesters. This means the United States is in a different place in Iraq today than in 2011. However, the killing of members of Kataib Hezbollah and the attacks straddling the Iraq-Syria border illustrate that a larger conflict is already taking place. This conflict has existed under the surface, involving Iran’s actions in the Gulf, and Houthi attacks on Saudi Arabia as well as Israeli airstrikes against Iran in Syria and Iraq. Kataib Hezbollah has been seeking to strike at the United States since May, when the rocket attacks began. At the same time, Iran is accused of transferring ballistic and other missiles to Iraq.

The PMU are at a crossroads after the U.S. strikes. They can choose to escalate the conflict and show that they are the new power behind the throne in Iraq, a sort of Iraqi version of Iran’s IRGC. Or Iran may seek to reduce tensions. Yet Iran will likely choose both options, as it has in the Gulf and in Syria. Trump has been reticent to commit more U.S. troops to foreign wars that he portrays as endless sunk costs. Iraq is a sunk cost in this estimation and Trump has said ISIS is defeated on the ground. That puts the United States in a complex position, wanting to maintain some presence in Iraq and southern Syria, but not wanting a large new conflict with Iran or Iran’s proxies. Five airstrikes were supposed to be a message of deterrence for the attack near Kirkuk. It shows the United States has been watching several Kataib Hezbollah’s sites for weeks or months. But Kataib Hezbollah didn’t evacuate its locations, assuming it was safe. This is the brinkmanship that could lead to a wider conflict. That conflict could stretch thousands of kilometers from the Gulf to Israel’s Golan Heights.

Seth J. Frantzman is a Jerusalem-based journalist who holds a Ph.D. from the Hebrew University of Jerusalem. He is the executive director of the Middle East Center for Reporting and Analysis and a writing fellow at Middle East Forum. He is the author of After ISIS: America, Iran and the Struggle for the Middle East (forthcoming Gefen Publishing). Follow him on Twitter at @sfrantzman.

Image: Reuters.