The US conducted a new round of airstrikes — the second in roughly a day — in Iraq early on Wednesday, destroying two facilities used by Iranian proxies that had been targeting American and coalition troops, US defence officials said.

The latest rounds in the tit-for-tat attacks between the US and Iranian-backed fighters took place in Iraq, in a departure from the US’s practice of striking mostly targets in Syria.

This time, the US struck an operations centre and a command-and-control centre node south of Baghdad used by Kataib Hezbollah, a militia group in Iraq that is considered a proxy of Iran. Kataib Hezbollah’s political wing is part of the coalition of Prime Minister Mohammed Shia al-Sudani of Iraq.

A defence official said the military could not provide a casualty assessment.

The US has escalated its strikes recently. On Monday night, an American military gunship fired on and killed three Iran-backed militants who the Pentagon said on Tuesday were part of an attack on US and coalition forces in Iraq. Unlike that exchange, which Pentagon officials said came at the spur of the moment after an American warplane in the area witnessed the ballistic missile attack on al-Asad air base and retaliated, the Wednesday morning strikes were planned, at least for a few hours.