Iran drew the attention of the world last week, with threats to obstruct the export of approximately one-fifth of the world's oil trade in response to harsh new US sanctions against its financial system.

Tehran's long-standing proclivity for bellicose rhetoric muted the impact on energy markets, where oil prices rose only modestly. But the episode highlighted the prospect of a new round of instability and conflict in the Middle East, at a time when the global economic recovery remains precarious.

The Obama administration will implement the new US sanctions gradually over the next six months, with a keen election-year eye on petrol prices and considerable flexibility, at least on paper, to avoid undercutting the global economic recovery.