BAGHDAD, Jan. 5 (Xinhua) -- Four mortar rounds on Sunday landed on the heavily fortified Green Zone in central Baghdad, an Iraqi Defense Ministry official said.
The incident took place in the evening when four mortar rounds hit the zone, which houses some of the main offices of the Iraqi government and the U.S. embassy, the official told Xinhua on condition of anonymity.
"One of the rounds landed at the bank of Tigris River close to the U.S. embassy," the source said.
The heavily fortified Green Zone has been frequently targeted by mortar and rocket attacks. The roughly 10 square km zone is located on the west bank of the Tigris River, which bisects the Iraqi capital.
Late on Saturday, Abu Ali al-Askari, security leader of the Iraqi Shiite militia Kata'ib Hezbollah (KH) warned the Iraqi security forces to move away from the U.S. bases with no less than 1,000 meters starting from Sunday.
"The leaders of the security services must abide by the safety rules of their fighters and not allow them to be a human shield," al-Askari said.
The latest attack came after a U.S. drone attack ordered by President Donald Trump killed Qassem Soleimani, commander of the Quds Force of Iran's Islamic Revolution Guards Corps, and Abu Mahdi al-Muhandis, deputy chief of Iraq's paramilitary Hashd Shaabi forces.
The attack took place on the Baghdad international airport's road early on Friday.
Iran's Supreme Leader Ayatollah Ali Khamenei and President Hassan Rouhani have vowed to retaliate against the U.S. over Soleimani's death.
Sunday's attack also came after Iraqi protesters on Tuesday stormed the U.S. embassy compound in Baghdad to protest the U.S. air raids conducted on Dec. 29 against five bases of Iran-backed militias in Iraq and Syria, claiming the lives of 25 militants.