Erbil International Airport FILE
CNN  — 

Six rockets landed near Erbil International Airport in the semiautonomous Kurdistan region in northern Iraq on Wednesday, according to a statement released by the Ministry of Interior of the Kurdistan Regional Government.

A US defense official with direct knowledge of the latest reports told CNN initial indicators are that three rockets struck a base where US troops are located, with additional rockets hitting outside the base. There are no reports of US injuries or damage so far.

The US has some initial indications the rockets may have been larger than those typically used, but officials are still trying to confirm that. The defense official called this attack “troubling” because of the number of rockets involved and the possible use of larger-scale weapons.

The rockets were fired from the direction of Sheikh Amir, a small town in Nineveh province, which is under the control of a predominantly Shia paramilitary force, Hashad al Shabbi, according to the to the Interior Ministry of the Kurdistan Regional Government. It said the rockets landed in a remote area without causing any casualties.

The Iraqi Defense Ministry released a statement adding: “On Wednesday evening, a terrorist group targeted Erbil Governorate with several missiles using a modified Kia four-wheel carrying a rocket launcher. It was ordered to arrest the security commander in charge of the area where the rockets were fired from, and an investigation was opened immediately.”

Prime Minister of the Kurdistan Region of Iraq Masrour Barzani, strongly condemned the rocket attacks, tweeting, “The KRG will not tolerate any attempt to undermine Kurdistan’s stability and our response will be robust. I have spoken to the Prime Minister of Iraq, Mustafa al-Kadhimi, on the importance of holding the perpetrators accountable.”

An Iraqi former deputy prime minister, Hoshyar Zebari, tweeted: “Another escalation to disrupt security in Iraq and Iraqi Kurdistan by the same groups who are attacking the US Embassy in Baghdad and its convoys. Actions is needed to stop it.”

The attack comes a day after CNN reported the Trump administration told Iraqi leaders at multiple levels that it would close the US Embassy in Baghdad if Iranian-backed militia attacks targeting US personnel in the country don’t subside, demonstrating the seriousness of the consideration, according to three US officials.

The threat to close the embassy – America’s largest in the region – has shocked Iraqi officials, especially as it came after what the country viewed as a successful visit to Washington last month. US officials said the administration will make a determination about the status of the embassy in the coming weeks, and any changes would require briefings to Congress.

Tensions between the US and Iranian-backed forces in Iraq skyrocketed before and after the killing of Iranian commander Qasem Soleimani in a US drone strike in Baghdad in January.

In response, Iran launched more than a dozen missiles at two Iraqi bases that hold US troops, prompting questions over whether the administration fully considered the fallout from such a strike, and if an appropriate legal basis was established for the presidential authorization of lethal force.

In March, two Americans and a British national were killed in a rocket attack on a military base in Taji, Iraq, that one US official said was likely the work of Iran.

It is unclear precisely how Iraq would move to drive down the militia attacks, and how quickly the Iraqis could take the necessary action. There is, however, more that the Iraqi security forces can do to combat the Iranian-backed militia attacks and provide protection to US facilities and personnel in the country, US and Iraqi officials said, but did not elaborate on specifics.

There are also fears that the reporting on these diplomatic demands could throw fuel on the fire and result in militia groups carrying out even more attacks, the US and Iraqi officials said.

This story has been updated with additional information Wednesday.

CNN’s Kylie Atwood, Jennifer Hansler and Paul LeBlanc contributed to this report.