A commander in the Revolutionary Guard states that the Strait of Hormuz between the Persian Gulf and the Indian Ocean is closed, and that all vessels attempting to pass will be set on fire. The question is whether the Revolutionary Guard can put force behind its words.

On Monday evening, the price of American light crude had risen by well over 7 per cent to just over 72 dollars per barrel. North Sea oil had risen by more than 8 per cent and was traded at close to 79 dollars.

The Norwegian krone has strengthened markedly following the outbreak of war in Iran and was on Monday at its strongest in three years.

Norway benefits from a higher oil price. It is the loss of Iranian oil and a blockade of Hormuz which, taken together, increase the oil price.