Michael Axworthy says the fall of IS would be good news, but what next? This article is part of a series exploring the question: What happens after Islamic State?

The fall of Islamic State (IS) would be a success for Iran. It would remove a dangerous enemy close to Iran’s borders. It would also strengthen Shi‘a allies in Iraq and help Syria as well as being one in the eye for the regional rival, Saudi Arabia. But it would not be an opportunity to push for regional hegemony.

What one thinks about the motivation and stance of the Iranian regime affects perceptions of how it will react to the collapse of IS. The Iranian regime is often characterised as a hegemonic, expansionist power that supposedly uses Shi‘a communities elsewhere in the region as an instrument for its own ends.

This characterisation is not plausible for two good reasons. First, Iran is not set up as a militarist or expansionist state. Iranian defence spending was 2.3% of GDP in 2012 according to the Swedish International Peace Research Institute – a typical yearly figure over the last decade or more. This is comparable with the UK – although the Iranian figure could be adjusted up by as much as .75% to include spending on the Revolutionary Guards. Saudi Arabia spending in the same year was 7.7% (10.4% in 2014), Israel 5.7%, United Arab Emirates 4.8%. Outside of the region, the figure for the US was 4.2% (for the Soviet Union in the 1980s – a truly militaristic state with which Iran is sometimes compared – 15–17%).

Second, if Iran were to seek to increase and exploit sectarian tensions for its own interests in an all-out intra-Muslim conflagration, Shi‘as and Iran would lose — Shi‘as are only 12–15% of Muslims worldwide.

The Iranian regime, like most others, wants (in priority order):

  1.  to secure its own rule within Iran
  2.  to protect Iranian national security
  3.  to protect Iranian and (where feasible) Shi ‘a interests outside Iran

Iran’s defence and security posture is essentially defensive but doesn’t always sound defensive. This is primarily down to the heritage of revolution and revolutionary rhetoric, especially under the former president Ahmadinejad. It is also due to Iran’s stance toward Israel.

For Shi‘a Muslims...defeat of IS will also be a relief. But they will be anxious about what happens next

Central to Iranian thinking (and any sound understanding of Iran’s position now) is the Iran-Iraq war (1980–88). Iran was invaded at a vulnerable moment, and it had few allies (only Syria, and Israel to some extent). By the end of the war, Iran was isolated and felt it was facing a global alliance of overt and covert enemies. The lesson drawn by Iranians was that Iran could defend itself and uphold self-determination (important for Iranians given a long previous history of invasion and humiliation) but only from its own resources. It could not, and cannot trust external powers to help, or even to keep their word.

A further lesson from the Iran-Iraq war is relevant. In 1982, having regained the territory lost to Saddam at the beginning of the war, the Iranians had a choice – whether to accept a ceasefire or to continue the war and remove the Iraqi leader, Saddam Hussein, from power.

After much debate, they chose the latter (encouraged by over-enthusiastic Revolutionary Guard officers). However, they overreached themselves, endured six more years of ultimately fruitless warfare with hundreds of thousands killed and more disabled. They were forced ultimately to accept a ceasefire on similar terms to that available in 1982.

Most Iranians, regime supporters or not, now accept that the decision to continue the war in 1982 was a mistake. That lesson of the perils of overreach and the wisdom of a more defensive posture will be uppermost in the minds of the regime leadership as they consider Iraq after IS.

For Shi‘a Muslims more widely in the region, the defeat of IS will also be a relief. But they will be anxious about what happens next. They will be concerned as to whether the defeat of IS will deepen the bitterness of Sunnis in Iraq that made possible the rise of IS in the first place.

The removal of IS will not remove the root causes of the rise of groups like al-Qaeda, Taliban, and IS in the region, and there is a risk that a new version of al-Qaeda or IS will bubble up.