A US contractor died of cardiac failure after rocket fire hit an Iraqi base hosting coalition troops Wednesday, the Pentagon said, just two days ahead of Pope Francis' visit to the country.

Around 10 rockets slammed into the sprawling Ain Al Assad military base in Iraq's western desert after several weeks of escalating US-Iran tensions on Iraqi soil.

"A US civilian contractor suffered a cardiac episode while sheltering and sadly passed away shortly after," the US Defence Department said, noting there were no current reports of injuries among US service personnel.

Francis was quick to say he would go ahead with the first-ever papal visit to the war-scarred country so as not to "disappoint" the Iraqi people.

"The day after tomorrow, God willing, I will go to Iraq for a three-day pilgrimage," the 84-year-old pontiff said in his Wednesday address. "For a long time I have wanted to meet these people who have suffered so much."

Ain Al Assad hosts Iraqi forces and US-led coalition troops helping fight the Daesh terror group. It is also a base for drones the coalition uses to surveil terrorist sleeper cells.

The base’s rocket system was "engaged in defence of our forces”, said the Pentagon, noting Defence Secretary Lloyd Austin had been briefed and was closely monitoring the situation.

Iraqi security forces were on the scene and investigating, but it was too early to attribute responsibility, it added.

The coalition’s spokesman said 10 rockets hit the base at 7:20am (0420 GMT) and Iraqi security forces said they had found the platform from which 10 "Grad-type rockets” were fired.

Western security sources told AFP the rockets were Iranian-made Arash models, which are 122mm artillery rockets and heavier than those seen in similar attacks.

The Iranian Tasnim news agency reported last year that the country’s Revolutionary Guard had developed the Arash because it was more precise than other models.

Probe implicates Hashed 

The US contractor’s death marked the third fatality in recent rocket strikes, after an attack targeting US-led troops in the Kurdish regional capital of Erbil left two people dead.

On Wednesday, Erbil’s counter-terror service said its investigation found members of the Hashed Al Shaabi, an Iraqi state-sponsored security force, were involved in that attack.

The Hashed includes hardline pro-Iran factions accused by both US and Iraqi officials of conducting previous rocket attacks on Western interests.

The attacks are typically claimed by shadowy groups that officials say were established to deflect blame from the real perpetrators.

One of these "front groups” claimed responsibility for the Arbil rockets, but Erbil’s counterterror service published a "confession” by a man it said was one of four people involved and who implicated the Hashed.

Days after that attack, more rockets hit a US military contracting company north of the capital and the US embassy in Baghdad.

In response, the US conducted an air strike on February 26 against Kataeb Hizbollah, an Iranian-backed Hashed unit stationed along the Iraqi-Syrian border, killing one fighter.

Analysts say hardline factions want to ramp up pressure on Prime Minister Mustafa al-Kadhemi following his pledges to rein in rogue militias.

Kadhemi tweeted after Wednesday’s attack that "any party that thinks it is above the state or can impose its agenda on Iraq and the future of its people is delusional”.

Observers also say the rockets may be Tehran’s way of pressuring Washington, which under President Joe Biden is offering to revive the Iran nuclear deal abandoned by his predecessor Donald Trump in 2018.

Iraq ‘waiting for us’ 

Tensions between the two arch-rivals peaked in January 2020 after a US drone strike on Baghdad killed Iranian general Qassem Soleimani and top Iraqi paramilitary commander Abu Mahdi Al Muhandis.

In response, Iran launched ballistic missiles on Ain Al Assad and Erbil, wounding dozens.

Over the next 10 months, dozens of rockets and roadside bombs targeted Western security, military and diplomatic sites across Iraq — some of them deadly.

Last year’s attacks came to a near-complete halt in October following a truce with the hardliners, but they have resumed at a quickening pace over the past three weeks.

Despite the attack and the COVID-19 pandemic, Francis said he would go ahead with his visit, which includes a meeting with top Shiite cleric Grand Ayatollah Ali Sistani.

"The Iraqi people are waiting for us, they were waiting for Saint John Paul II, who was forbidden to go,” said the pontiff, who is not set to visit west Iraq.

"One cannot disappoint a people for the second time. Let us pray that this journey will be successful.”

To control the crowds during the pope’s visit, Iraq is set to extend weekend lockdowns to cover the entire papal visit from March 5-8.