The US on Wednesday condemned the assassination of Iraqi academic Husham Al Hashimi and called on the government to bring his killers to justice.
Al Hashimi, who advised the government on security matters, was shot dead by two men at his house in Baghdad on Monday.
“Iraq tragically lost a patriot, prominent scholar and journalist, Husham Al Hashimi, who devoted his life to a free and sovereign Iraq and gave voice to the aspirations of the Iraqi people,” US Secretary of State Mike Pompeo said during a press conference.
A peaceful protest was held on Tuesday evening in Baghdad's Tahrir Square to honour Al Hashimi as Iraqis and international colleagues mourned his loss.
Protesters held signs which read: "They assassinated the voice of truth with a fake bullet", and on social media videos circulated of TukTuk drivers sounding their horns outside his home in a show of solidarity and support.
The killing triggered fears that Iraq could enter a violent phase, as tensions between pro-Iranian factions and the government of Prime Minister Mustafa Al Kadhimi increase.
In the days leading up to the assassination, Al Hashimi was repeatedly threatened by Iran-backed armed groups, Mr Pompeo said. He called on the government of Iraq to “bring to justice the perpetrators of this terrible crime and bring them swiftly to justice.”
The US embassy in Baghdad said in a Facebook post that it was "deeply shocked and saddened by the cowardly murder" and offered "deepest condolences to his family and to the people of Iraq for the tragic loss of this Iraqi national treasure".
Al Hashimi’s killing sparked widespread outrage. The UN, foreign governments and Iraqi leaders have all condemned his assassination and urged the prime minister to find those responsible and hold them to account.
Al Hashimi, 47, was known for his expertise on Al Qaeda, ISIS and other armed groups in Iraq.
He wrote about terrorist groups, including three books, and advised Iraqi governments past and present.
Al Hashimi had been working closely with the new prime minister and was a member of the Iraq Advisory Council – a panel of experts and former policymakers.
Government officials described his death as a “targeted killing” but did not blame any group.
"We vow to his killers that we will pursue them so they are justly punished," the prime minister's office said.