With the dramatic advance of Iraq’s insurgents from Mosul towards Baghdad, an equally sensational development has been heralded: the US and Iran may ally to check the threat to the Iraqi government.
Will Washington and Tehran set aside 35 years of animosity and declarations of confrontation across the Middle East? Can their opposed military forces be joined in attacks on the Islamic State of Iraq and other Iraqi factions?

Probably not – if there is US–Iran co-operation, it will be far more discreet and limited than the headlines foresee. 

1. The background: a shared interest in Iraq
The US and Iran have each accused the other of trying to dominate Iraq, especially since the American-led invasion of 2003. However, both share the interest of keeping the Iraqi government in control. 

For Washington, Prime Minister Nuri al-Maliki has been the best option for a ‘strongman’ to maintain a supposed stability as American troops left Iraq. 

For Tehran, the Shia leadership in Baghdad bolsters the political and economic ties between Iraq, with its majority Shia population, and the Islamic Republic, the most prominent Shia-led regime in the world. 

2. The scenario
Iranian ground forces – up to 2,000 troops and militia – and commanders have been significant in the Iraqi government’s attempt to hold back the insurgency. These include two battalions of the elite Quds Forces and its commander Qassem Soleimani. 

This Iranian presence could be complemented by US airpower, with intelligence on the ground assisting Washington’s strikes. US and Iranian commanders could exchange ideas and information on the status of Iraqi forces. 

The US and Iran could also co-ordinate political advice to the al-Maliki government. Washington has insisted that military intervention must be accompanied by reform and a pursuit of ‘unity’, and Iran has been unhappy that al-Maliki’s quest for power has antagonised other groups – including important Shia elements – in Iraq. 

3. The challenge within the US
Unsurprisingly, any prospect of co-operation with a long-time ‘enemy’ will be anathema to many US politicians and groups. While some Congressmen have put aside hostility, others like John McCain – presidential candidate in 2008 – have rejected any dialogue with Tehran. 

The Obama Administration is far from united on the approach to Iran. The State Department is in favour, but the Pentagon at this point is opposed to any plans. 

Opponents of co-operation believe that the big victor of a US–Iran campaign against insurgents will be the Islamic Republic, whose political and economic interests in Iraq will not only be preserved but boosted – at the expense of Washington and other regional powers. 

4. The challenge within Iran
Even greater than the obstacles within the US are those within Iran. 

The Rouhani government initially invited the US to discuss co-operation: ‘We are very influential in Iraq, Syria, and many other countries.’ 

The backlash was immediate. Speaker of Parliament Ali Larijani, often used as a channel for the Supreme Leader’s views, said the US was responsible for ‘terrorism’ and the Iraqi insurgency. So did the chair of the National Security Council and the head of Iran‘s armed forces. 

These denunciations may be for public consumption, while the government tests possibilities in private. However, the Supreme Leader’s view of a ‘dishonest’ US is entrenched. Iran, having seen US troops depart after almost a decade, is unlikely to be receptive to a long-term return of American power – particularly given the crisis in neighbouring Syria and Tehran’s declaration of a ‘front-line’ defence from Iraq through Lebanon. 

5. The nuclear opportunity?
Even the scenario of a collapse of Baghdad’s authority is unlikely to propel a US–Iranian alliance. Setting aside obstacles to co-operation, there is little room in a rapidly shifting conflict for plans which require more than a day or two for development and implementation. 

Instead, US–Iranian discussions are more likely to be over Iraq’s political future if the insurgency can be checked. 

This is where opportunity may come from negotiations on a different topic: Iran and the 5+1 Powers, including the US, are currently seeking a comprehensive nuclear agreement. 

If there is progress towards a deal – and it is a big ‘if’ – then the environment becomes more conducive for US–Iran co-operation. With a perception of mutual interest, if not ‘trust’, the two powers could concentrate on Iraq, as well as Syria. There is a precedent: in the small window between 9/11 and the US invasion of Iraq, Washington and Tehran held discussions on the future on Afghanistan. 

A glimmer of possibility came on Monday, when US and Iranian officials used nuclear talks in Vienna for a brief conversation about Iraq. 

Right now, however, that conversation is little more than a grasping of straws. The situation in Iraq is serious for both the US and Iran, but it is probably not serious enough to quell their rivalry for position in Iraq and the Middle East – and far from serious enough to break down the domestic resistance to co-operation. 
Scott Lucas, Professor of American Studies,
University of Birmingham