Saudi Arabia has temporarily shut its East-West oil pipeline after a drone attack, cutting a key route the kingdom has used to bypass shipping disruptions through the Strait of Hormuz, according to Reuters.

The 1,200-kilometer pipeline carries crude across Saudi Arabia to the Red Sea and has transported between 4 million and 5 million barrels per day (bbl/d) in recent months, equivalent to around 4%-5% of global oil supply.

The Saudi Energy Ministry said it closed the pipeline as a precaution. Saudi Arabia and Iraq said the drone attack originated from Iraq, where Iranian-backed militias operate. Saudi authorities reported injuries and damage, which they were assessing.

The pipeline has played a major role in maintaining Saudi crude flows during the six-month US-Iran war, which has reduced tanker traffic through Hormuz. The shutdown adds pressure on Saudi exports as shipping risks also increase around the Red Sea and Bab el-Mandeb.

Saudi crude supply had already fallen by 2.3 million bbl/d to 6 million bbl/d in August, its lowest level in more than three decades, according to the International Energy Agency (IEA).

The East-West pipeline has also supported Saudi crude shipments through Egypt. In June, it was reported that crude transported to Yanbu could move by tanker to Ain Sokhna before crossing Egypt through the SUMED pipeline to Sidi Kerir on the Mediterranean for re-export.

Reliance on this route later increased. In August, more than 70% of Saudi Arabia’s daily crude exports were redirected to Yanbu, while Saudi crude accounted for around 90% of loadings at Sidi Kerir during a record week.