The United States has launched its first airstrikes in nearly a decade against the Iran-backed militia forces in Iraq and Syria.

The Pentagon said it hit five bases used by the Iraqi Hizbollah militant group following a rocket attack in Iraq that killed a US civilian contractor.

Three of the bases were in Iraq, and two in Syria, where the militia has been trying to bolster the regime of President Assad.

“US forces have conducted precision defensive strikes against five KH facilities in Iraq and Syria that will degrade KH’s ability to conduct future attacks against OIR coalition forces,” the Pentagon said.

Secretary of State Mike Pompeo said the strikes send the message that the US will not tolerate actions by Iran that jeopardise American lives.