Since the beginning of the year, a total of 43 attacks have targeted military bases housing international coalition troops, foreign embassies and Iraqi convoys carrying logistical support, AFP reported.
The latest of which was on Sunday (June 20) when a rocket attack targeted Ain al-Asad air base in Anbar province.
Some of these attacks appear to be direct attacks against the Iraqi government, such as the rocket barrage that hit Baghdad's Green Zone in February.
All these attacks are widely blamed on Iran-linked militias, particularly Kataib Hizbullah and the "smokescreen" militias under its command.
The United States is offering a reward of up to $3 million for information on these strikes.
But the impact of the rocket and drone attacks would be much greater if not for the air defence systems put in place by the international coalition, experts said.
The counter rocket, artillery and mortar (C-RAM) air defence systems deployed in the Green Zone and at air bases in Iraq destroy enemy projectiles in midair.
The US-supplied C-RAM systems have "greatly reduced the risks of these indiscriminate rocket attacks", political analyst Ghanem al-Abed said.
On June 6, a C-RAM system shot down two drones that were fired at Ain al-Asad base, the Iraqi military said.
Several hours earlier, a rocket targeting the Baghdad Diplomatic Support Centre was shot down above Baghdad airport "without causing casualties or damage", the international coalition said.
'Above the state and the law'
"Kataib Hizbullah and the rest of the factions affiliated with the Islamic Revolutionary Guard Corps (IRGC) have become a major threat to Iraq's stability and future," he said.
He described the militia as "a disorderly armed force that considers itself above the state and the law".
"It is responsible for most of the attacks against government offices and embassies in the Green Zone in central Baghdad," he said, as well as on Iraqi army bases hosting international coalition forces.
These forces are there to fight the "Islamic State of Iraq and Syria" (ISIS), he said, noting that the attacks on them are of "a provocative nature" aimed at undermining the security forces.
Many of the rockets and missiles used by Iran-backed militias have landed on houses in the vicinity of military bases and civilian compounds, causing civilian casualties and severe damage, he said.
But the impact would have been graver if not for the air defence systems in place, he added.
The Iraqi government is working to "confront the militias by pursuing and prosecuting their leaders", al-Abed said.
Efforts are focused on "restricting armed displays, stopping the harmful activities of all [Iran-backed] groups, led by Kataib Hizbullah, and blocking their economic interests", he added.
On May 26, after the police intelligence arrested Qasem Muslah, paramilitary operations chief for Anbar, the militias deployed armed men and armoured vehicles to the July 14 bridge that leads to the Green Zone to protest the arrest.
Responding to the provocation, Minister of Defence Jumaa Inad pointed out that "the Iraqi army has capabilities allowing it to fight a country, so what chances does a group of people in 40 unarmoured vehicles stand against it?"
'Language of violence'
"Kataib Hizbullah is always pushing to cast Iraq into a cycle of crises and problems that weaken its security and sovereign institutions," said journalist Ziad al-Sinjari.
"This militia and all the groups that follow Iran are trying to assert themselves by force of their rogue weapons," he said.
"They speak only the language of weapons and violence, and refuse to comply with the law or follow the decisions of the government and judiciary."
This is not the first time the militias have defied state orders and deployed their heavily armed elements in the streets of Baghdad in an attempted show of force.
On March 25, Rubu Allah, one of several pro-Iran militias that are generally understood to be fronts for Kataib Hizbullah, Harakat al-Nujaba and Asaib Ahl al-Haq, staged a military parade in Baghdad.
But this did not go over well with many Iraqis.
"With every instance of lawlessness provoked by the militias, especially after the arrest of one of their leaders, there are repeated demands to seize their weapons and reduce their illegal activities, which undermine security," he said.