A key oil pipeline system in Saudi Arabia was struck by projectiles on Thursday, according to two US officials familiar with the matter.

Saudi Arabia’s Ministry of Energy said in a statement posted to its website Friday that the pipeline had been attacked and “was shut down as a precautionary measure.”

An early analysis found that pump stations, which are located next to the pipeline itself, were hit, one of the US officials said. A satellite image taken Friday appears to show extensive fire damage at one pumping station, and an image of a different pumping station, taken Thursday, showed a small fire sending up plumes of thick, black smoke.

It was not immediately clear who was responsible for the strikes or if sections of the pipeline itself were damaged but one of the officials said it was struck by drones originating from Iraq.

The strike signals that the kingdom’s oil resources — and its ability to export those resources — are facing increasing threats as the Iran War continues. The attacks on the pipeline come within days of an Iranian-aligned militia’s seizure of a strategic Red Sea port city in Yemen that could further threaten energy shipping in the region.