Once Greece goes, most analyses of the exit process say it will be painful but containable, as long as it does not spread.

BBC: Euro talks: The last signal before the storm?

That would be even more likely, if the short-term mess resulting from a "Grexit" turned out to be containable, as many hope but none can confidently predict.

BBC: Sir Mervyn, the UK and the euro

But even should this happen, the crisis (and Americans' understandable demand for retaliation) will be more containable if the United States and Europe have settled their own differences and formed a common, less generalised, approach to Iran and if Iran's new president has clearly signalled that he is prepared to listen to and act on the West's concerns.

ECONOMIST: Iran��s new face