Saudi Arabia has shut down a critical pipeline used to bypass the Strait of Hormuz, adding another threat to already strained Middle Eastern crude supplies.

Saudi Arabia halted operations on its East-West pipeline as a precaution after multiple attacks on the system, according to the kingdom's Energy Ministry. The Saudi Foreign Ministry later said the pipeline had been targeted by drones launched from Iraq, according to The Wall Street Journal.

The roughly 750-mile pipeline carries crude from fields in eastern Saudi Arabia to the Red Sea port of Yanbu, allowing exports to avoid the Strait of Hormuz. The pipeline's importance has increased as shipping through Hormuz has been disrupted by the Iran war.

The news arrived after oil had spent much of Friday retreating. Prices had given up their earlier gains after reports that Middle Eastern officials were discussing a temporary deal with Iran that could make it easier for ships to pass through Hormuz.

Brent futures settled down 2.8% on Friday at $104.61 a barrel, and were trading around $104.47 a barrel in post-settlement trading.

Energy stocks were subdued. By Friday's close, the Energy Select Sector SPDR fund was up 0.3%. Chevron gained roughly 0.6%, while ExxonMobil Holdings and Occidental Petroleum were up 0.5%. ConocoPhillips increased 0.2%.

The larger question now is how long the pipeline remains offline. With Hormuz already constrained, a prolonged disruption would remove one of Saudi Arabia's most important alternative routes for getting crude to global markets.