Iran is once again misbehaving - its nuclear programme is causing concern within the international community. Its decision to reopen its uranium enrichment facility in Natanz has been seen as another step towards a nuclear crisis - one that Iran, the Middle East and indeed the whole world can ill afford.

Enriched uranium can be used to manufacture nuclear weapons or it can be used for civil nuclear power. However, this latest development marks another move by the regime of President Mahmoud Ahmadinejad away from the 2004 Paris Agreement reached with the so-called EU3 - the UK, Germany and France. The agreement involved the suspension by Iran of all sensitive nuclear work while negotiations on the future of the county's nuclear programme continued with the European powers.

Iran's talks with the EU3 had already broken down last year after Teheran had resumed its production of uranium hexaflouride gas - the step before enrichment - at its Isfahan plant. According to the International Atomic Energy Agency (IAEA) this was clearly in breach of the Nuclear Non-Proliferation Treaty, which Iran is a signatory to, and which states that while countries have the right to develop nuclear power for peaceful purposes, this must be done under the strict supervision of the IAEA.

Mark Fitzpatrick, a Senior Fellow for non-proliferation at London's International Institute for Strategic Studies (IISS) remarked: "We're at a crisis point. The Paris Agreement is dead." According to the IISS, Iran could develop enough weapons-grade uranium to develop a nuclear weapon within five years. It is more than obvious that the international community will not allow this to happen - whether further diplomacy, sanctions or military action will be resorted to still remains to be seen.

However, it is clear that the international community, the IAEA, the United Nations, the European Union and the United States, not to mention Israel, are running out of patience with Iran. "Today Iran has taken another deliberate step towards uranium enrichment - the process for creating nuclear bomb material. The regime continues to choose conflict over co-operation - a choice that deepens the isolation of Iran and harms the interest of the Iranian people," Greg Schulte, the American Ambassador to the IAEA, said recently.

Of course, there are no easy solutions to this problem, but something has to be done. Iran is now led by a President who claimed the Holocaust was a myth and who said Israel should be wiped off the face of the earth. Can you imagine the consequences of a nuclear-armed Iran led by Mr Ahmadinejad? The most likely option now would be taking Iran to the UN Security Council and imposing sanctions on Tehran, although there is no guarantee that Russia - which has a nuclear co-operation accord with Iran - and China will agree to this.

European diplomacy had achieved some results under the old Iranian regime led by President Khatami, but everything changed with the election of hard-liner Ahmadinejad last June. Two and a half years of European diplomacy effectively went down the drain - as certain American conservative hawks had said would happen - although it is fair to say that these talks went nowhere because of a change in direction by Iran.

So basically it is correct to say that diplomatic efforts to make Iran co-operate have probably run their course. Iran feels that the international community is divided over how best to deal with this issue and is in no mood for another confrontation after what happened in Iraq. Iran knows that the US does not want to further antagonise the Shi'ites in southern Iraq who have close links to Tehran and it believes Europe and America will never see eye to eye over Iran. It is probably assuming that countries like Russia and China are reluctant to confront Iran and would rather concentrate on improving their commercial ties with the Islamic Republic.

A firm and united international response to Iran's latest behaviour is therefore absolutely crucial and Russia has very important role to play in this dispute. During a meeting between President Vladimir Putin and German Chancellor Angela Merkel in Moscow last week Mr Putin said Russia, the US and Europe held "close positions" on the issue. He also backed statements by his Foreign Minister, Sergei Lavrov, that Russia did not exclude the possibility of referring Iran to the Security Council. However, he also signalled that Iran had not rejected a Russian proposal to set up a joint Iranian-Russian project on Russian territory to provide fuel - uranium enrichment - for Iran's nuclear programme. This option, if agreed to by Iran, offers a slim hope of a diplomatic solution, but I wouldn't count on Tehran accepting this request.

In the meantime the EU3 have made it clear that they are to call for an extraordinary meeting of the IAEA on February 2 to refer Iran to the Security Council where it will probably be ordered to completely suspend its nuclear programme. Should Iran fail to do this punitive measures could be imposed, including sanctions, that is, if Russia votes in favour of such sanctions. China has so far resisted the idea of involving the Security Council, but would probably vote in favour or abstain if Russia does likewise. Should the UN fail to impose sanctions it is possible that the EU would impose its own sanctions.

Sanctions have had mixed results in the past and it is not easy to predict their effect on the Iranian situation. A lot depends on what type of sanctions are imposed. There could be travel sanctions against members of the Iranian government and a freezing of Iranian assets abroad. There could also be economic and trade sanctions but these are unlikely to be approved by the Russians and Chinese. One also has to consider whether sanctions would result in rallying the Iranian people in favour of the regime, which is not what the international community wants to achieve.

Then there is the military option, which could take place if everything else fails. The obvious country to carry out such a course of action is Israel. An attack of this sort will not have the blessing of the UN, but it will have Washington's approval and that is all Israel needs. Shortly before his massive stroke Israeli Prime Minister Ariel Sharon had declared: "Israel will not accept a nuclear weapon equipped Iran". It is said that Mr Sharon had secretly ordered the Israeli Defence Forces to be ready to launch air strikes against Iranian nuclear facilities if this became necessary. Israel's special forces are also said to be ready to fly into Iran by helicopter to sabotage the underground targets that cannot be bombed from the air.

There will naturally be many serious consequences following an American-backed Israeli attack on Iran. Terrorism against Israel and US targets will increase, the Muslim world and Iranian public opinion will be infuriated, the Shi'ites in Iraq will make more trouble for the Americans and Iran could retaliate against Israel using all kinds of weapons. As usual in these situations, there are certainly no easy options.