Analysts with ING financial group outlined four possible avenues for Iran: full escalation that also draws in other nations such as China or Russia; disruption of the Strait of Hormuz; active or passive support for terrorist attacks in the U.S. and Europe; or taking no action at all.

The scale of any energy price rises, and the wider impact, will depend on the magnitude of what comes next in the conflict between Israel and Iran. But it does have the potential to be "a bad shock for the global economy at a bad time" says Mohammed El-Erian, chief economic adviser at asset manager Allianz.