BAGHDAD, Aug. 27 (Xinhua) -- Three Katyusha rockets on Thursday landed in the heavily fortified Green Zone in the Iraqi capital Baghdad without causing casualties, the Iraqi military said.

The rockets were fired from the al-Bejiyah area in western Baghdad in late Thursday night and landed in the Green Zone, the media office of the Iraqi Joint Operations Command (JOC) said in a brief statement.

The rockets caused no casualties as they landed on an empty field in the zone, the statement said.

The attack is the second in the night as the JOC reportedly said that a rocket was fired from al-Dora highway in the south of the Green Zone but failed to reach the zone and landed in the al-Jadriyah neighborhood without causing casualties.

No group has so far claimed responsibility for the attack, but the military bases housing U.S. troops across Iraq and the Green Zone in Baghdad have been frequently targeted by mortar and rocket attacks.

The Iraqi-U.S. relations have witnessed a tension since Jan. 3 when a U.S. drone struck a convoy at Baghdad airport, which killed Qassem Soleimani, former 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 U.S. airstrike prompted the Iraqi parliament on Jan. 5 to pass a resolution requiring the government to end the presence of foreign forces in the country.

More than 5,000 U.S. troops have been deployed in Iraq to support the Iraqi forces in the battles against the Islamic State (IS) militants, mainly for training and advisory purposes.