Saudi Aramco has moved quickly to restore production at the world’s largest oil processing plants, reassuring customers of adequate supplies only days after devastating drone attacks that knocked out more than half of Saudi Arabia’s crude production.

Energy Minister Prince Abdulaziz bin Salman on Tuesday promised that output would return to normal by the end of September.

Half of the production lost in Saturday’s pre-dawn devastating strikes, blamed by the US on Iran, was already back on line. Aramco had dipped into its stored reserves to ensure supply continued as normal.