Massive Ordnance Penetrator

As part of a multi-billion-dollar request for more military spending earlier this week, the Pentagon asked for $88m to develop the Massive Ordnance Penetrator, a huge bunker-busting bomb, for its Stealth bombers. The Bush administration said the bomb was needed "in response to an urgent operational need for theatre commanders".

Democratic members of Congress questioned whether the weapon was intended for use against Iran, where nuclear facilities are largely hidden underground.

Jim Moran, a Democratic member of the House of Representatives' defence spending committee, said: "My assumption is that it is Iran, because you wouldn't use them in Iraq, and I don't know where you would use them in Afghanistan. It doesn't have any weapons facilities underground that we know of."

The immediate impact of the sanctions announcement will be felt in the boardrooms of banks and companies in Britain and elsewhere in Europe. Any business continuing to trade with Iran risks US reprisals.