The United States imposed sanctions Friday on three Iranian-backed Iraqi militia leaders over their alleged role in violently suppressing protests that have shaken Iraq.

The militia leaders are accused of ordering their forces to fire on civilians protesting government corruption and high unemployment. Since the protests began in October, around 400 protesters have been reported killed by security forces.

"Peaceful public dissent and protest are fundamental elements of all democracies," Treasury Secretary Steven Mnuchin said in a statement that announced the sanctions Friday.

In a subsequent statement, Secretary of State Mike Pompeo said: "The Iraqi people want their country back. ... They are calling for genuine reform and accountability and for trustworthy leaders who will put Iraq's national interests first. Those demands deserve to be addressed without resort to violence or suppression."

The sanctions target two brothers, Qais al-Khazali and Laith al-Khazali, from the Asaib Ahl al-Haq Iran-backed militia, as well as Husayn Falih Aziz al-Lami, who was accused of running a militia on behalf of Iran's Islamic Revolutionary Guard Corps.

The Trump administration will consider imposing further sanctions if violence against Iraqi protesters does not stop, according to David Schenker, assistant secretary of state for Near Eastern affairs.

"We are not done. This is an ongoing process," Schenker told reporters Friday.

The punitive measures also targeted an Iraqi businessman, Khamis al-Khanjar, for alleged bribery and corruption.

The sanctions allow the U.S. government to freeze any assets the men might have in the United States and bar Americans from doing business with them.

The protests in Iraq have led to the resignation of Prime Minister Adel Abdel-Mahdi, an ally of Iran. Along with economic concerns, the protesters are also demonstrating against what they perceive as increasing Iranian influence in Iraqi affairs.