The Guardian | Patrick Wintour: In November 2018, Donald Trump tweeted: �Oil prices getting lower � a tax cut for America and the world! Enjoy! $54 � Thank you to Saudi Arabia.�

Five months on, with oil prices more than $70, Trump will be in a less celebratory mood as Opec�s oil ministers and their allies gather in Jeddah on Friday, without Iran. The main agenda item will be the implications for oil of three interconnected American foreign policy crises � in Venezuela, Iran, and Libya. Together these crises, being played out simultaneously, have the potential to scrub as much as 3.5m barrels of oil per day from the markets.

Rarely has there been a moment when a US foreign policy has had so much potential to cause such dislocation to oil markets, and as a result to hand so much market power to America�s Gulf allies to exploit that belligerence.

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