Iraqi security forces arrested more than a dozen pro-Iran fighters overnight, in their first raid against those accused of anti-U.S. rocket attacks. Elite fighters from the Counter-Terrorism Service raided a headquarters in southern Baghdad used by Kataib Hezbollah, a pro-Iran faction also identified as Brigade 45 of the Hashed al-Shaabi military force.

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

Iraqi government officials and paramilitary sources then gave contradicting versions of what followed. The paramilitary sources and one government official said those detained were transferred shortly afterward to the security branch of Iraq's paramilitary umbrella grouping, the Popular Mobilization Forces (PMF). A second government official denied any such transfer and said the militiamen were still in the custody of other security services. The sources gave different numbers for those detained. A PMF official said it was 19. A government official said it was 23.

The raid was the first sign that the government of Iraq's new prime minister, Mustafa al-Kadhimi, intends to make good on pledges to take tough action against militia groups that have targeted U.S. installations.

Since October, nearly three dozen attacks have targeted American interests in Iraq, including a range of military bases, the U.S. embassy in Baghdad and U.S. oil companies. They have killed Iraqi, U.S. and U.K. military personnel. The U.S. has blamed Kataib Hezbollah for the attacks and has retaliated twice, in both cases after rockets killed U.S. military personnel stationed at Iraqi bases. Washington has pressured Baghdad to take tougher action against the group.

The CTS was set up by U.S. occupation forces following the 2003 invasion that toppled Saddam Hussein and is largely seen as a force friendly to Washington. Its commander, Abdulwahab al-Saadi, was appointed last month by PM Kadhimi, and both men are considered by Washington as allies. Under the new premier, Iraq and the U.S. launched a strategic dialogue earlier this month to discuss military, economic and culture issues. As part of the talks, Washington pledged to continue reducing the number of US troops in Iraq as part of the international coalition helping Iraq fight jihadist sleeper cells. Last year, there were 5,200 U.S. troops in the country but that number has dwindled as the U.S. has pulled back from Iraqi bases and paused training due to COVID-19.

Iraq, meanwhile, pledged to hold the perpetrators of the rocket attacks accountable and Kadhimi recently convened his national security council to draw up a plan. But the start of the talks coincided with a significant spike in missiles, with six incidents targeting American installations over the last two weeks. The escalation shattered the relative calm that had settled in since March, after a period of particularly high tensions between Iran and the U.S. spilt over into Iraq.