Truly, it will be an historic encounter. Not since the Shah was replaced by Ayatollah Khomeini’s hardline Islamic theocracy in 1979 has a British prime minister met with an Iranian leader.Yet David Cameron is now making entreaties to the enemy and planning to meet Hassan Rouhani at the UN General Assembly in New York this week.This, remember, is a country that has sponsored terrorism against the West on myriad occasions, has declared that Israel should be wiped from the map, and was famously labelled – along with Iraq under Saddam and North Korea – a member of the Axis of Evil by George W Bush.Its nuclear ambitions so terrify Western leaders that they have imposed sanctions that have devastated Iran’s oil exports and revenues.But times change, and now the West needs Iran, regarding it as a crucial potential ally in the fight against IS.Iran is reaching out too. Ever since Rouhani replaced his predecessor Mahmoud Ahmadinejad as president in August 2013, he has been trying to bring Iran back in from the cold.Ahmadinejad’s bellicose anti-Western rhetoric during the eight years of his rule ensured the country’s deepening isolation on the international stage.And while Rouhani may be a plausible figure, the regime’s religious hardliners are still uniformly grim, imposing their moral puritanism on a young, vibrant and educated population which, behind the scenes, enjoys partying, illicit drinking and casual sex.Last year Iran executed 624 people for various offences, some of them publicly strangled as they were hoisted aloft by large crane. Torture is commonplace and stoning seen as just punishment.Yet Cameron is clearly in the mood for conciliation and his diplomatic offensive throws up a number of questions.Why would Iran want to help the West in its fight against IS? Can its forces really help? And what kind of concessions would the Iranians demand in return for discreetly siding with the coalition of Western and Arab countries now launching air strikes on IS’s headquarters in the Syrian city of Raqqa?There is no doubt that Iran wants to see the back of IS. Its Shia-led regime considers Iraq and Syria as allies – both are also governed by Shia Muslims. IS’s butchers are all extreme Sunni Muslims, deadly rivals of the Shia, and Iran rightly believes them to be a dangerously destabilising force in the Middle East.Officially Iran is not part of the efforts to degrade and destroy IS – America is still seen as the Great Satan by its hardliners who will not countenance US troops back in Iraq.But covertly the country’s head of ‘subversive warfare’ – 56-year-old General Qassem Suleimani, supremo of the elite Iranian Quds force – is already working alongside his US counterpart General Mick Bednarek in Baghdad’s Green Zone.Members of the Iranian Revolutionary Guard are also hidden among the sizeable Shia militias defending the holiest Shia shrines in Iraq such as Karbala and Najaf, while Iran has warned IS to stay away from its own borders.To consider whether Iran can help defeat IS, we have to examine the force they would be taking on.Obama has made an analogy between IS and cancer. By 2010, Western and Iraqi special forces had eliminated all but 10 per cent of Al Qaeda in Iraq as a result of capturing or assassinating their operatives.But that 10 per cent rump metastasised into IS under their leader Abu Bakr al-Baghdadi who decided to exploit the civil war in Syria as a source of recruitment, funding and territory. Two thirds of its 30,000-strong army now lurk there.Our intelligence agencies failed to detect how this army organised from its Syrian base a systematic assassination campaign of Iraqi army and police chiefs, or a series of spectacular prison breaks, including one at the notorious Abu Ghraib jail where Iraqi prisoners were tortured by their Western captors.Few noticed how in January IS fought off an Iraqi army force of several divisions trying to recapture the Iraqi city of Fallujah. Long before they captured Mosul this August, IS was raking in £5million a month through nightly extortion in this huge city.The IS leadership consists of hardened Al Qaeda veterans, but the tactical sophistication derives from a group of former generals who served under Saddam Hussein.They have used Iraq’s modern road network to bring to bear their core spearhead of about 3,000 men, who soften up targets with vehicle-borne suicide bombers wiping out command and control centres. Social media bring fear and terror to a Shia-dominated Iraqi national army, whose corrupt officers have stolen their soldiers’ pay.Those demoralised soldiers simply flee, or are murdered. IS are also formidable in defence. They blow up bridges and unleash controlled floods to hamper counter-attacking forces, while using IEDs to defend approaches in the way regular armies would use mines.Worse, IS anticipates their enemies. They knew Obama’s air-strikes on Raqqa were coming, and will have moved their command and control centres to outlying villages. They thwart the West’s recruitment of moderate Sunni rebels. IS’s online multi-lingual magazine Dabiq (The Ark) suggests neutralising any attempts to turn the local Sunni tribes against them by co-opting them into their own administration – and it’s a tactic that’s worked.Syria’s President Assad – with his sponsor Iran’s tacit approval – was notified in advance of the air strikes, and warned that his entire air defence system would be obliterated if he objected. But why should Assad object anyway, if his most deadly opponents are being eliminated?Yet air strikes will not be enough. Ground troops will have to be involved. Which is why Obama, who can at least rely on the help of Kurdish Pesmerga forces and durable elements of the Iraqi army, is now pumping £300million into a new force of ‘moderate’ secular-minded Syrian tribes, 5,000 of whom will be rapidly trained in Saudi Arabia.This throws up its own problems. The moderates have been fighting against IS alongside another extremist group Jabhat al-Nusra - which was itself targeted by US airstrikes this week because of fears they were accessories to planned terrorist attacks.Throw in the Iranians, and the confusion over loyalties becomes even greater. Many of the Sunni moderates Obama is trying to woo consider Iran’s Shia regime a greater enemy than IS. This means it would be impossible for Iranian troops to engage overtly in Iraq or Syria – it would incite fury among the Sunni in those countries.Cameron’s talks with Rouhani will be a negotiator’s minefield. Cameron will want him to stop backing Assad but Rouhani will never concede to giving up on such a long-standing Shia ally.Rouhani will want to persuade the West to relax sanctions in return for help against IS. Yet any movement to accommodate Iran’s nuclear programme could infuriate Israel. And Israel, if provoked, could destroy the West/Arab coalition.Yet despite all this, despite the fact that Cameron knows he is supping with the devil, he is right to engage with Rouhani.IS presents an existential threat to the entire region and must be beaten. And Iran is such a major power that it is far better to try to enlist its help and keep its president onside than to continue to treat it as a pariah.(dailymail.co.uk)Bakudaily.Az