“There are deeply authoritarian characters in the Iranian regime who would have no hesitation in using extreme violence against protestors” says Dr Nader Hashemi, assistant professor of Islamic politics at the University of Denver, reflecting on how the Iranian authorities might react should tens of thousands gather in Vali-Asr Square this Sunday to mark the second anniversary of the so-called ‘stolen election’. “There are also loyal ideological troops who, if ordered, would massacre everyone in the Square in the name of nationalism,” he adds.

We don’t know what will happen on Sunday. This week the Coordination Council of the Green Movement called on Iranians to participate in silent protests across the country with the biggest demonstration expected in Tehran, where protesters will march across the city in absolute silence. The size of the turnout is hard to predict. Many people will certainly be energised by the unfolding Arab Spring and emboldened by the demonstrations of on February 14 held in solidarity with Tunisia and Egypt and in defiance of the authorities. But those demonstrations, which turned into the first anti-government street protests in more than a year, also resulted in the house arrest of the main leaders of the opposition movement, Mir Hossein Mousavi and Mahdi Karroubi.

These house arrests have combined with an effective strategy of targeted arrests of student activists, intellectuals, journalists and the lawyers who would normally represent them, severely curtailing the organisational capacity of the Green Movement. This, combined with fear of arrest and violence together with a wider fatigue and loss of political momentum might conspire against the mobilisation of large numbers of demonstrators. “I would not expect enormous crowds on the streets to mark the second anniversary, but then neither would I be surprised if there were an attempt to gather them,” says Paul Ingram, executive director of the British American Security Information Council. “I think it would be a mistake, however, to judge the health of the movement by its ability to pull people onto the street on any particular day” he adds.

The demands set out by the Coordination Council are for the release of political prisoners and the movement’s leaders, the holding of free elections and action to tackle high prices and unemployment. If demonstrators do come out on Sunday their core grievances, non-violent methods and democratic aspirations will have much in common with other movements across the region. Indeed the Green Movement is regarded by many as a key catalyst for the Arab Spring. Whilst Iran’s rulers publicly express support for the pro-democracy uprisings, privately they are deeply concerned about the effect they will have on both internal and regional politics, particularly if their beleaguered ally Bashar Assad of Syria were to fall.

Another problem for the Green Movement comes in the shape of the recent ratcheting up of tensions over Iran’s alleged nuclear ambitions. Since the 2009 elections the democratic issue has taken priority over the nuclear issue for many ordinary Iranians. However, there is huge popular support for Iran’s civil nuclear programme across a broad spectrum of opinion in Iran. Nuclear fuel production is regarded as a sovereign right and a source of great national pride and many Iranians believe that western allegations of a weaponisations programme are being used for political purposes. According to Paul Ingram, “international attempts to punish Iran for pursuing nuclear fuel production simply strengthen the legitimacy of the government’s stance to defy those attempts, as well as the very legitimacy of the government itself.”

At the end of May the International Atomic Energy Agency (IAEA) released two reports which claim Iran is continuing to stockpile low-enriched uranium in defiance of UN sanctions and is failing to provide adequate transparency to resolve outstanding questions on its nuclear programme. On Monday IAEA chief Yukiya Amano said that he had “received further information related to possible past or current undisclosed nuclear-related activities that seem to point to the existence of possible military dimensions to Iran's nuclear programme." President Amadinejad dismissed this speculation, accusing Amano of taking orders from Washington, and on Wednesday Iran announced that it would shift its production of higher grade uranium to an underground bunker and triple its production capacity.

President Netanyahu made his desire for military action against Iran fairly plain during his speech to the US Congress last month and Obama is no doubt coming under increasing pressure to take a hard line against Iran not just from Congress but from within his own party. Like the conservative Iranian leadership, neo-conservative policymakers in Washington are concerned by the sudden and unprecedented rise of people power sweeping the Middle East. Whilst they may pay lip-service to pro-democracy movements the loss of influence in the region resulting from the Arab Spring has convinced them that the need to attack Iran and reassert US power is more urgent than ever.

Assessing the state of Iran’s nuclear enrichment programme at a meeting in Parliament last year Saba Sadeq, head of the BBC’s Persia service, argued that, “both sides are exaggerating Iran’s nuclear capacity for their own motives.” A year on and the political landscape has shifted significantly, largely down to the unexpected Arab Spring. The standoff between Iran and the West over enrichment may have been bumped off the headlines recently but it has not gone away. Indeed with increased tensions over the nuclear issue simultaneously serving both the interests of western neo-conservatives and Iranian hardliners there is a danger that it may soon come to a head. The main losers as tensions mount will be the pro-democracy and civil society movements within Iran. “The Iranian leadership would benefit from an Israeli military strike,” says Dr Hashemi. “And it would spell disaster for the Green Movement.”