In Iran, the government has ordered its supporters to stage nationwide demonstrations today to express their hatred for the opposition Green Movement, which earlier this week made a dramatic reappearance on the streets of Tehran to demand the overthrow of President Ahmadinejad’s regime.

That was hardly the response the clerics were hoping for when they extolled the protests in Egypt, comparing events with their own Islamic revolution in 1979. Ayatollah Ali Khamenei, the Supreme Leader, claimed earlier this month that the overthrow of Hosni Mubarak was part of the same “Islamic awakening” as the events of 32 years ago in Iran.

Once the crowds of demonstrators and chants of “Death to the Dictator” appeared on his own doorstep, he rapidly backtracked. Within a few hours, the order had gone out to the broadcast media to halt all coverage of unrest elsewhere in the Middle East. The next day, in a rowdy session of parliament, government MPs called for the execution of the Green Movement’s leaders, including Mir Hossein Mousavi, a former prime minister, and Mehdi Karroubi, the parliament’s former speaker. So much for free speech.

The re-emergence of the Green Movement is certainly a major embarrassment for the government. The mullahs no doubt assumed that their uncompromising response had silenced the protests that erupted in the wake of the disputed presidential election in 2009. Indeed, over the past few months, their executioners have been fully occupied with those accused of organising the protests, many of whom were sentenced to death on trumped-up charges such as drug-smuggling.

Iranian opposition groups estimate that the majority of the 89 people executed in January – the highest rate of any country in the world – were anti-government activists. They included Sahra Bahrami, a 46-year-old Dutch-Iranian woman, detained during the 2009 protests. She was hanged on bogus drug-smuggling charges, causing the Dutch government to freeze all ties with Iran.

The opposition has shown this week that it refuses to be cowed by the brutality of the regime’s response. But of more concern for Iran’s ruling elite will be fresh signs of a split within the ranks of the Republican Guards, the organisation formed specifically to protect the revolution.

In a letter to Mohammad Ali Jafari, the Guards’ hardline commander, a copy of which has been seen by The Daily Telegraph, senior officers seek reassurance that “we will not [have to] shoot nor beat our brothers seeking to express legitimate protest against the policies and conduct of their leaders”.

To date, the officers, who are based in Tehran, Isfahan, Qom and Tabriz, have received no official response from Mr Jafari, who has passed the letter to the Supreme Leader’s office. But any suggestion that the guardians of the Islamic Revolution might be unwilling to fight their own countrymen raises serious questions about the ability of both Mr Khamenei and Mr Ahmadinejad to survive a renewed bout of protests.

What ultimately sealed Mr Mubarak’s fate was the refusal of his military to fire on the protesters in Tahrir Square. It is not beyond the bounds of possibility that the same could happen in Iran.

Another rogue state reeling from the wave of protest is Libya, where Colonel Gaddafi has dominated the country for 41 years. This week’s demonstrations, in the eastern cities of al-Bayda and Benghazi, were sparked by the arrest of a human rights lawyer who was campaigning for the families of more than 1,000 prisoners killed by the security forces 15 years ago.

Saif al-Islam Gaddafi, the dictator’s second son and heir apparent, is said to have confided to his advisers that he is sympathetic to the protesters’ demands for wholesale reform of what he calls the “false politics” of the Arab world. But that is unlikely to be much help to those participating in today’s “Day of Anger” against the regime. Libya’s security forces are notorious for their brutality: when students at Benghazi University protested against Gaddafi’s rule in the 1980s, the revolt was ruthlessly crushed, and the ringleaders hanged from lamp-posts on the campus.

The challenge for Western governments now is to decide how best to encourage regime change in rogue states such as Iran and Libya while trying to contain it in pro-Western states like Bahrain. The inherent problem has been evident in President Obama’s conflicting responses to the protests in Bahrain and Tehran. In the latter case, Mr Obama has actively encouraged protesters to take to the streets; when it came to Bahrain, a long-standing ally which plays host to the US Fifth Fleet, Mr Obama was more circumspect, merely encouraging the King to address the grievances of his people. As protests continue to sweep across the region, it is not just the governments of the Middle East that are struggling to respond.