Saudi Arabia’s crude oil supply fell by 2.3 million barrels per day (mmbbl/d) to 6 mmbbl/d in August, its lowest level in more than three decades, as attacks disrupted energy facilities and regional shipping routes, the International Energy Agency (IEA) reported to Reuters.

The decline contributed to a wider drop in OPEC+ production, which fell by 1.8 mmbbl/d to 38.8 mmbbl/d during August amid attacks on Saudi energy infrastructure and a U.S. blockade on Iran.

Houthi-linked groups struck vessels passing through Bab el-Mandeb, the Jazan refinery and shipping near Yanbu, while Iran-backed militias in Iraq used drones to strike the Abqaiq oil processing complex.

Further risks emerged after Iran-aligned Houthis seized control of Yemen’s port of Mocha, adding another threat to oil and commercial shipping through the Red Sea.

The disruptions have limited OPEC+ members’ ability to meet their production targets despite earlier plans to return more barrels to the market.

Earlier in September, OPEC+ kept its October production policy unchanged as the Iran war continued to restrict regional oil exports. Saudi Arabia, Russia, Iraq, Kuwait, Algeria, Kazakhstan and Oman agreed to maintain the policy.

That decision followed the completion of a phased reversal of 1.65 mmbbl/d in voluntary cuts in September. However, actual OPEC+ production remains below targeted levels as regional disruptions restrict supply, leaving the group with less control over the amount of oil reaching global markets.