One source told Iranian media that the attack had three messages.
Much is known about the details of an attack on March 3 that targeted US forces in Al-Asad base in Iraq. A truck was used. Ten rockets were placed in the truck’s bed and then a false bed was put on top of them to obscure them. This was a method used in the past by pro-Iranian militias. The rockets were 122mm and are an Iranian type. Iran was likely behind it by operationalizing one of its local militias.
However the key questions remain about which militia carried out the attack and what the militias expect will come next. One source told Iranian media that the attack had three messages. One is that it is in revenge for an airstrike the US carried out in Syria in February. That airstrike was itself a response to an attack on US forces in Erbil in Iraq in mid-February. The second and third messages are designed to challenge the US “occupation” of Iraq. The pro-Iranian “resistance,” led by Kataib Hezbollah in Iraq is thus sending messages.
But the US is not being hasty in saying who did it. This is because naming names requires actually doing something. If a person ordered it, or Tehran, then more airstrikes on warehouses and bases in Syria would not be an appropriate response. Yet the US knows from long experience that Iran uses Iraq as a kind of “near abroad” battleground to bleed the US. Iranian-backed militias have killed hundreds of Americans in Iraq since 2003. Iranian-backed groups used to use the infamous “EFPs” that exploded and killed Americans a decade ago. Later these roadside bombs were altered. Now Iran uses 107mm and 122mm rockets.
The questions facing the Pentagon is also about force protection. The US withdrew from most facilities in Iraq. But it wants to continue to have a footprint at Union III in Baghdad, at Al-Asad and in Erbil. It expected to be safe in Erbil. However the US lacks many of the key components of a multi-layered air defense system to stop these rockets. Iran is using the same kinds of munitions it advised Hezbollah and Hamas to use against Israel. However, Israel has developed Iron Dome and other systems to stop them. The US has Patriots for longer range ballistic missiles and it has C-RAM for shorter range munitions. But the US doesn’t appear to want to move more air defense to Iraq. This leaves US forces and Coalition contractors a bit at the mercy of Iran.
The key questions linking Iran to the attacks, such as signals intelligence or some kind of courier that brings the orders to Kataib Hezbollah, and the planning structure or even the garage where the rocket trucks are assembled, are key parts of Iran’s threats in Iraq. Finding those would require more cooperation from Iraq’s government. So far Iran continues to get the plausible deniability it wants with the rocket attacks in Iraq. The US is even loathe to launch airstrikes the way Trump’s administration did in Iraq.