Iran-backed militant groups launched four more attacks against US bases in Iraq and Syria on Thursday with rockets and drones, but there were no casualties or damage.

Reuters quoted a US official, who spoke on the condition of anonymity, as saying that US and international forces were attacked at two sites in northeastern Syria with multiple rockets and a one-way attack drone. Since war broke out between Israel and Hamas, Iranian proxy forces have launched more than 70 such attacks, leaving many servicemen injured.

In Iraq, multiple one-way drones were launched at the Ain Al-Asad airbase west of Baghdad and a drone was launched at a base housing US force near Erbil airport in northern Iraq.

A group calling itself the Islamic Resistance in Iraq, which analysts say is a catch-all for several Iran-aligned Iraqi armed groups, had claimed attacks on those locations earlier in the day.

The attacks come the day after the U.S. struck the Iran-aligned Kataeb Hezbollah (KH) armed group south of Baghdad in an attack that KH said had left eight members dead.

The attack was condemned by the Iraqi government as escalatory and a violation of sovereignty.

US officials said the United States had struck Iran-backed groups after an escalation in their attacks that have targeted US and international forces dozens of times. The US has retaliated just a handful of times.

As of Thursday, there had been 36 attacks in Iraq and 37 in Syria, the US military official said.

Iran has avoided direct military involvement in the war, but has used its network of armed groups to target both Israel and US forces in the region.