It’s sad to see my old friends at London’s Daily Telegraph publish such an idiotic editorial as “Iran’s Actions Will Only Increase Its Isolation”.

In fact, Iran remains entirely un-isolated. Everyone apart from Washington treats it as a normal state, no matter what it does. At any given time, it has at least two and usually three Security Council vetoes in its pocket, which is more pals than the Americans or British can count on at that table. If the Royal Navy gets it chaps back, Her Majesty’s Government will resume the usual parade of ministerial grandees jetting in to Teheran to profess their admiration for the Islamic Republic.

Back at the start of Jimmy Carter’s hostage fiasco, I think it was Andrei Gromyko who remarked that, if the students had pulled the same stunt at the Soviet embassy, Tehran would have been a crater by lunchtime. The Iranians believed him so he never had to do it (though, as Chechnya indicates, the Russians are generally prepared to walk the walk crater-wise). Obviously, if Blair or Bush were to threaten to reduce Tehran to a crater, the mullahs would most likely conclude, on balance, that we didn’t mean it.

That is the core problem for the guarantors of the global order: we have to find a way of demonstrating our will that has credibility. A hyperpower whose national legislature has spent the last year discussing the best way to achieve bipartisan consensus on the best form of defeat in Iraq cannot be surprised when it isn’t taken seriously in the world. A leading second-rank power whose troops are kidnapped and publicly humiliated cannot wait a week and then react by tentatively talking about talking to the EU about talking to the UN about talking about a sanctions resolution.

Without this incident, Britain would have spent the last week marking the 25th anniversary of the Falklands War. As John O’Sullivan recounts in his excellent book The President, The Pope And The Prime Minister, there was a real “Falklands effect” in the wake of that war: Nobody thought the toothless old British lion would fight back and re-take the islands, especially after the humiliations inflicted by Iran on America, embodied by Jimmy Carter as a smiling eunuch. Neither Iran nor the Falklands had any direct connection with the Cold War, but the former marked the depths of western self-enfeeblement and the latter the dividing line between the territorial losses of the Seventies and the rollback of the Eighties.

Realists talk a lot about “deterrence”. But you can’t deter if you have no credibility. And that’s what bleeds away in London and Washington every day.