WASHINGTON -- The Pentagon said on Sunday that the US military carried out strikes against Iran-backed military group in Iraq and Syria, two days after a rocket attack on an Iraqi base leading to the death of a US civilian contractor.

US forces have conducted "precision defensive strikes" against three Kata'ib Hezbollah (KH) facilities in Iraq and two in Syria, Assistant to the Secretary of Defense Jonathan Hoffman said in a statement.

These targets included weapon storage facilities and command and control locations that KH uses to plan and execute attacks on Operation Inherent Resolve (OIR) coalition forces, the statement added.

The Pentagon pointed out that the military raid was a response to the KH rockets attack on an Iraqi base near Kirkuk on Friday, which resulted in the death of a US citizen, injured four US service members and two members of the Iraqi Security Forces (ISF).

KH has a strong linkage with Iran's Quds Force and has repeatedly received lethal aid and other support from Iran, according to the statement.

More than 5,000 US troops have been deployed in Iraq to support the Iraqi forces in the battles against Islamic State (IS) militants, mainly providing training and advising to the Iraqi forces.

The troops are part of the US-led international coalition that has been conducting air raids against IS targets in both Iraq and Syria.