Iran has dismissed accusations by the United States that it was behind drone strikes on Saudi Arabia's oil plants.
President Trump's warned the US is "locked and loaded" to respond to the attacks.
Oil prices surged by at least 15 per cent following the attack which knocked out 5 per cent of the world's supply.
Yemen's Houthi rebels have claimed responsibility for the drone strike.
Saudi Arabia oil supply was attacked. There is reason to believe that we know the culprit, are locked and loaded depending on verification, but are waiting to hear from the Kingdom as to who they believe was the cause of this attack, and under what terms we would proceed!
— Donald J. Trump (@realDonaldTrump) September 15, 2019