A partial view of the Iraqi capital Baghdad is reflected in the visor of a US Army helicopter crew member as he looks out of a Chinook helicopter flying from the US Embassy to Baghdad International airport on January 9, 2019. Courtesy: Andrew Caballero-Reynolds

A rocket was fired into the Iraqi capital Baghdad’s heavily-fortified Green Zone, which houses government buildings and foreign embassies, on Sunday but caused no casualties, the Iraqi military said.

A Katyusha rocket fell in the middle of the Green Zone without causing any losses the military said in a statement, later specifying that it landed near the Monument of the Unknown Soldier.

The blast was heard across central Baghdad on Sunday night, according to Reuters witnesses and residents.

The Katyusha multiple rocket launcher is an inexpensive type of rocket artillery that can deliver explosives to a target quicker than conventional artillery, but is less accurate.

Police special forces found a rocket launcher in eastern Baghdad’s al-Sina district, about 7 km (4.3 miles) away across the Tigris River from the Green Zone, and sealed off the area, a police source told Reuters.

Officers were searching for suspects and an ordinance disposal team from the Baghdad Operations Command was on its way to inspect the launcher, the source said.

Capt. Bill Urban, a spokesman for US Central Command, said it was aware of an explosion in the Green Zone outside the US Embassy compound, and that there were no US or coalition casualties.

The Monument of the Unknown Soldier is about half a kilometre (a third of a mile) north of the sprawling US embassy compound.

The embassy in Baghdad and the US consulate in the Iraqi Kurdish regional capital Erbil evacuated non-emergency staff this week, out of apparent concern about perceived threats from Iran.

President Donald Trump’s administration has said it sent additional forces to the region to counter what it called credible threats from Iran against US interests, including from militias it supports in Iraq.

Tehran has described US moves as “psychological warfare” and a “political game.”

Both Iran and the United States have said they do not want war.

Hours after the blast in Baghdad, Trump wrote on Twitter: “If Iran wants to fight, that will be the official end of Iran. Never threaten the United States again!”

The Green Zone was regularly targeted by mortars during the US occupation of Iraq that ended in 2011.

Rockets have occasionally been fired into the Green Zone since then. The latest such incident was in September, when three mortar shells landed inside the Green Zone, causing no casualties.