Rockets struck Iraq's capital Tuesday with four landing inside the heavily fortified Green Zone killing a child and wounding at least five people, Iraq’s military said.
It signalled an end to an informal truce announced by Iran-backed militias in October.
Two Iraqi security officials said one of the rockets that hit the Green Zone struck close to Iraq's National Security Service, which is located around 600 meters from the American Embassy.
Some of the rockets were intercepted by the C-RAM air defence system installed by the US earlier this year, they said.
Iraq's military said three rockets landed outside the Green Zone, one hitting close to Baghdad Medical City hospital, one at the gate of a public park, and a third exploded in the air. One child was killed and five civilians were wounded, the military statement said.
Officials said two Iraqi security forces personnel were also wounded inside the Green Zone. They spoke on condition of anonymity in line with regulations. There was no immediate claim of responsibility.
The military said the incident would not go without "prosecution and accountability."
US troops invaded Iraq in 2003 and left in 2011 but returned in 2014 after the so-called Islamic State group overran large parts of Iraq.
Frequent attacks targeting the US Embassy and vehicles transporting equipment for US troops have led Washington to threaten to close its Baghdad diplomatic mission and sparked a diplomatic crisis prior to the US presidential election.
The attack comes after a recent announcement by the Pentagon that it would reduce troop levels in Iraq from 3,000 to 2,500.