Iraqi Shi’ite Muslim men from the Iran-backed group Kataib Hezbollah march in a Quds Day parade, in Baghdad, July 25, 2014. Photo: Reuters / Thaier al-Sudani.

Iraqi security forces raided a stronghold of a powerful Iran-backed militia in southern Baghdad late on Thursday and detained more than a dozen members of the group, government officials and paramilitary sources said.

The raid was the most brazen action by Iraqi forces against a major Iran-backed militia in years and targeted the Kataib Hezbollah group, which US officials accuse of firing rockets at bases hosting US troops and other facilities in Iraq.

It signaled that new Prime Minister Mustafa al-Kadhimi, whose government is negotiating Iraq’s security, political and economic ties with Washington, intends to fulfill pledges to rein in militia groups that have attacked US installations.

Kadhimi took office in May with the support of both Tehran and Washington, but faces a tough balancing act between Iraq’s two main allies, whose mutual hostility has repeatedly threatened to send the region into further conflict.

The military said the raid, carried out in the middle of the night by the US-trained Counter Terrorism Service, was directed at militiamen suspected of firing rockets at foreign embassies in Baghdad’s fortified Green Zone and its international airport.

Iraqi authorities were questioning the 14 men detained during the raid, it said. The incident took place after a number of rocket attacks near the US embassy in Baghdad and other US military sites in recent weeks.

The raid’s aftermath showed how hard it may be for Kadhimi to take on Iran-backed militias that have come to dominate large parts of Iraq’s security establishment, politics and economy.

After the operation, unidentified gunmen drove vehicles towards government buildings and a headquarters of the CTS, the military said, as paramilitary officials demanded the release of the detained militiamen.

Conflicting accounts

Tensions between Washington and Tehran especially on Iraqi soil have been high for at least a year.

It nearly spilled into regional conflict in January after the United States killed Iran’s military mastermind Qassem Soleimani and Iraqi paramilitary chief Abu Mahdi al-Muhandis in a drone strike at Baghdad airport.

Kadhimi says he will not allow Iraq to become a theater for a US-Iran showdown.

Iran-backed parties and factions have shown rising hostility to Kadhimi, who is due to travel to the United States in coming weeks as part of talks over Iraq’s ties with Washington.

The United States has been reducing the number of its troops stationed in Iraq which are tasked primarily with fighting Sunni Muslim Islamic State militants — a mutual foe of Baghdad, Washington, Tehran and the Shi’ite militias Iran backs.

Before the military issued its statement about the raid, Iraqi government officials and paramilitary sources had given contradicting versions of what happened.

The paramilitary sources and one government official said those held were sent to the security branch of Iraq’s Popular Mobilization Forces (PMF), a paramilitary umbrella grouping.

The PMF is an Iraqi state institution. It contains factions loyal to Iran and others that are not, but has been dominated by Iran-aligned militias.

A second government official denied any such transfer and said the militiamen were still in the custody of other security services. One PMF source initially said 19 men had been detained. A government official said it was 23.

One government official told Reuters three commanders of Kataib Hezbollah had been detained during the raid. One of those commanders was an Iranian, he said.

The PMF source denied this, saying no commanders of Kataib Hezbollah were detained and no Iranians.