"The President has no higher priority than the safety of U.S. personnel, and he directed today's action to make clear that the United States will defend itself, its personnel, and its interests," Austin said, presenting the new action as yet more retaliation for the series of attacks on US bases in the region since the Gaza war began.

The Sunday night statement further detailed these targeted facilities were "used by Iran's Islamic Revolutionary Guard Corps (IRGC) and Iran-affiliated groups" believed behind most of the attacks on US installations in Iraq and Syria.

The day prior, US defense officials had revealed US bases have been targeted 48 times since October 17, which has resulted in 56 American service personnel injured, albeit with minor injuries.

The first major US airstrikes on eastern Syria occurred on October 27, with the second round following on November 8. The Biden administration had at first touted that these would "deter" further aggression on US troops, but have clearly not, given the missile and drone attacks have only continued.

US officials have meanwhile ratcheted their rhetoric against Tehran, saying the Iranians will ultimately be held responsible, but Tehran officials have denied being behind the spate of attacks.

Of last week's strikes, a Pentagon press secretary said US airstrikes had taken out an "IRGC-linked weapons storage facility". This was in response to rockets and suicide drones launched on US bases, which have totaled at least two dozen instances in Iraq and over two dozen instances in Syria.