This BBC analysis wonders just how effective the world can be in keeping Iran from recognizing its nuclear ambitions.

An excerpt:

Any sanctions would be mainly economic. Their effect is questionable. And there are several stages to be gone through before they could be imposed.

To start with, Western countries have to agree among themselves that Iran's decision to remove UN seals and resume uranium enrichment research crosses a red line and means the end, for now at least, of diplomacy.

The EU three - Britain, France and Germany - which have been negotiating with Iran have reached that conclusion.

Then the West and its allies have to persuade the wider membership of the UN nuclear supervisory agency, the International Atomic Energy Agency (IAEA), to agree to refer Iran to the UN Security Council.

Refused

Then the Council, if it is sufficiently united, is likely only to issue a warning to Iran before taking any other action. It would probably tell Iran to suspend all activities again and re-enter negotiations.

Only if Iran refused would sanctions then be drawn up.

What kind of sanctions? They would be trade-orientated, aimed primarily at the one major industry that Iran has - its oil and gas.

French Foreign Minister Philippe Douste-Blazy (l), German Foreign Minister Frank-Walter Steinmeier (2nd l), UK Foreign Secretary Jack Straw (2nd r) and EU Foreign Policy Chief Javier Solana
EU foreign ministers have called for action on Iran's nuclear activity

Iran is also currently applying for membership of the World Trade Organization (WTO), so this application would be blocked. The application is at an early stage. A working party to examine it was set up only last year but all that work would in effect stop.

The United States already embargoes major trade with Iran. It is especially keen to stop US oil companies from helping Iran develop its reserves.

Oil and gas are by far Iran's largest exports. According to the WTO, they and mining products account for 86% of Iranian exports.

But the US could not expect other countries to take such drastic action and it might be difficult to persuade some of them to take much action at all.

For example China, a veto-holding permanent member of the Security Council and in search of oil worldwide, would hardly vote for an oil embargo - given that in November 2004, it reached a major agreement with Iran to buy its oil and gas in a deal valued by the Chinese at $70bn.