There are several instructive parallels between this episode and the Arab Spring, which has occurred during President Obama's term in office and has seen several Middle Eastern autocrats, including US allies, challenged and even toppled by their countrymen.

The first parallel pertains to background attitudes. Both presidents projected weakness and sent the wrong messages. Their aspirations to rid the world (including America) of nuclear weapons, the pressure they both put on Israel, and their shared preference for humanitarianism over force, signalled a diminished confidence in the virtues of American and allied strength.

Carter's attitude was noted by the counter-terrorism force charged with training to rescue the hostages in Iran, known as Delta Force. The unit had not expected to be deployed by an administration so repulsed by the notion of force. As one of its members pointed out, Carter had said at the outset of the crisis, "We will do nothing to jeopardise the lives of those hostages." What he should have said was, "All options are on the table." The choice of words reflected the administration's attitude: several months into the crisis, as the use of force became unavoidable, the pacifistic secretary of state, Cyrus Vance, felt obliged to resign.

His deputy, Warren Christopher, responded with incredulity to a briefing by Delta Force's commander, who explained that the unit planned to scale the embassy walls and "take out the guards".