Consider the following scenario. A group of Irish republican terrorists carries out a bombing raid in London. People are killed and wounded. The group escapes, first to Ireland, then to the United States, where they disappear into the sympathetic hinterland of a country where IRA leaders have in the past been welcomed at the White House. Britain cannot extradite them, because of the gross imbalance of the relevant treaty. So far, this seems plausible enough.

But now imagine that the British government, seeing the murderers escape justice, sends an aircraft carrier (always supposing we've still got any) to the Nova Scotia coast. From there, unannounced, two helicopters fly in under the radar to the Boston suburb where the terrorists are holed up. They carry out a daring raid, killing the (unarmed) leaders and making their escape. Westminster celebrates; Washington is furious.

What's the difference between this and the recent events in Pakistan? Answer: American exceptionalism. America is subject to different rules to the rest of the world. By what right? Who says?

Consider another fictive scenario. Gangsters are preying on a small mid-western town. The sheriff and his deputies are spineless; law and order have failed. So the hero puts on a mask, acts "extra-legally," performs the necessary redemptive violence and returns to ordinary life, earning the undying gratitude of the local townsfolk, sheriff included. This is the plot of a thousand movies, comic-book strips, and TV shows: Captain America, The Lone Ranger, and (upgraded to hi-tech) Superman. The masked hero saves the world.

Films and comics with this plot-line have been named as favourites by many presidents, as Robert Jewett and John Shelton Lawrence pointed out in The Myth of the American Superhero and Captain America and the Crusade Against Evil .

The main reason President Obama has been cheered to the echo across the United States, even by his bitter opponents, is not simply the fully comprehensible sense of closure a decade after the horrible, wicked actions of 11 September 2001. Underneath that, he has just enacted one of America's most powerful myths.

Perhaps the myth was necessary in the days of the wild west, of isolated frontier towns and roaming gangs. But it legitimises a form of vigilantism, of taking the law into one's own hands, which provides "justice" only of the crudest sort.

In the present case, the "hero" fired a lot of stray bullets in Iraq and Afghanistan before he got it right. What's more, such actions invite retaliation. They only "work" because the hero can shoot better than the villain; but the villain's friends may decide on vengeance. Proper justice is designed precisely to outflank such escalation.

Of course, proper justice is hard to come by internationally. America regularly casts the UN (and the international criminal court) as the hapless sheriff, and so continues to play the world's undercover policeman. The UK has gone along for the ride.

What will we do when new superpowers arise and try the same trick on us? And what has any of this to do with something most Americans also believe, that the God of ultimate justice and truth was fully and finally revealed in the crucified Jesus of Nazareth, who taught people to love their enemies, and warned that those who take the sword will perish by the sword?

Formerly Anglican Bishop of Durham, in 2010 the Rt Revd Dr N.T. Wright was appointed to a Chair in New Testament and Early Christianity in the School of Divinity at the University of St Andrews, Scotland. He is one of the world's most distinguished and influential New Testament scholars. Among his many books are The New Testament and the People of God (1992), Jesus and the Victory of God (1996), The Resurrection of the Son of God (2003), Surprised by Hope (2007) and Virtue Reborn (2010).