Option: U.S. nuclear attack on Iran

Dan Plesch, Research Associate at the London School of Oriental and African Studies, has said that nobody doubts that the US is determined to stop Iran from become nuclear-armed.

He gave a speech analysing the options recently and told the BBC News website: 'The United States has the capability to come out of the clear blue sky and destroy the Iranian military infrastructure.'

He went on: 'You can say we are being hysterical and are a band of doom-mongers. But I fear the US has lost confidence in the UN or the EU to solve this. And it could do it militarily.

All this does not mean it will happen. It does mean it is being debated. "