On Saturday evening, three rockets hit the Iraqi air base at Balad, north of Baghdad, injuring an Iraqi contractor at the site. The attack was confirmed by Iraqi security officials who were not authorised to speak to the media, but told Reuters that the rocket strike resulted in one casualty. The latest attack comes after a large salvo of rockets was fired at the US army base at Erbil International Airport on Monday night, killing a contractor working with US forces. An obscure militia group, Saraya Awliya Al Dam, later claimed the attack, which several analysts spoken to by <em>The National</em> believed was linked to Iran. Iraqi news service Sabreen, which is thought by several analysts to be linked to Iran-backed militant group Asaib Ahl Al Haq, quickly claimed that the attack had occurred with "three Katyusha rockets". "Katyusha" —a reference to WW2 era Soviet rockets —is a catch all term used by Iraqi groups to refer to modern unguided rockets that can be launched in large salvos. Most of the devices are made in Iran or China. If Sabreen's claim is correct, it means the attack was smaller than the attack in Erbil on Monday night, which used a large number of Iran-made Fajr-1 rockets. The claim by Sabreen also suggests ISIS - who have been active in the Balad area - were not responsible. If an Iran-backed group has targeted Balad air base, the incident will represent another affront to the Iraqi government's authority and its ability to control militia groups. Balad air base of is huge strategic importance to Iraq, hosting around 34 F-16 fighters purchased from the US in late 2011, although the first fighters did not become operational until 2014. Despite delays finalising the sale of the aircraft due to opposition from US congress during the tenure of former PM Nouri Al Maliki, Iraq's F-16 programme has been relatively successful, with the aircraft conducting numerous air strikes on ISIS. This success has been largely dependent upon support from US weapons manufacturer Lockheed Martin and US aviation contractor Sallyport Global, which works with the Iraqi air force to keep the planes maintained and operational. Iraq's contract with Sallyport has been plagued by corruption allegations, and the project has seen further setbacks as tensions between Iran-backed groups and the US in Iraq have escalated. US contractors have been evacuated on several occasions, notably following the killing of Iranian general Qassem Sulaimani in a US drone strike on January 3 last year. These incidents could make it more difficult for the US and Iraq to keep the aircraft serviceable, a significant blow to Iraq's nascent airpower. Iraq's F-16s have cost the government at least $4 billion, including maintenance costs, ground crew and pilot training. Saturday's rocket attack on Balad is not the first of its kind: in January 2020 four Iraqi soldiers were injured at the base in a similar attack, which damaged some of the aircraft.