Concerns about the potential fallout (no pun intended) of Donald Trump’s potential withdrawal from the Iran nuclear agreement which (amongst other things) saw a lifting of international sanctions against Iran and its return to the crude oil suppliers’ market has been credited with pushing crude oil prices to their strongest levels for three years. The worry is that if the US left the agreement, Iran would again be subject to sanctions and global oil supplies would be restricted. This analysis is uncertain since US allies are trying to persuade America to continue with the accord and it is unlikely that they would follow the American lead without evidence that Iran had not been honoring the agreement. Were this to be the case, the US would be alone in issuing any future sanctions against Iran on this basis. However, markets have never been logical beasts. The benchmark Brent Crude has been trading fractionally above $75 per barrel before falling back.

By way of context, the current price is quite modest. In July 2008, Brent crude hit $145.61 a barrel, its record high. The lowest price for Brent was just $2.23 in May 1970, before the oil crisis sent prices rocketing. The collapse in the oil price which started in the summer of 2014 saw it fall from above $110 to a low of $34 in January 2016. The factors behind the decline included an oil glut, caused by declining global demand after the Global Financial Crisis; American shale oil coming on line; and stock market jitters.

Donald Trump has now gone on social media to complain that oil prices are “artificially very high” and the Opec cartel is to blame. To the extent that Opec and other oil exporting nations agreed to reduce output to support the oil price in 2017, an agreement that will expire by the end of 2018 unless extended, he is right. The text of Mr. Trump’s tweet states:

“Looks like OPEC is at it again. With record amounts of Oil all over the place, including the fully loaded ships at sea, Oil prices are artificially Very High! No good and will not be accepted!”

The president’s intervention was enough to knock Brent back from its recent highs, dropping by 1%. It is being seen as the latest episode of the new bellicose attitude to global trade.