Elisabeth Kendall focuses on the fortunes of al-Qaeda and IS in Yemen, and observes that this war-torn country could provide the ideal location for retreating IS fighters. This article is one of a series exploring the question: What happens after Islamic State?

Although several pockets of Islamic State (IS) operate within Yemen, it is not currently the dominant group in any region of the war-torn country, even within militant jihadist circles.

The most active branch of IS in Yemen over recent months has been Wilayat Aden-Abyan, but even here it is unclear the extent to which IS atrocities are stoked or even designed by political opponents of President Hadi’s government to exacerbate discord.

While IS in Yemen has carried out mass-casualty attacks that have grabbed the headlines, it is al-Qaeda in the Arabian Peninsula (AQAP) that has the upper hand in Yemen in terms of numbers, influence and appeal.

Soon after the Saudi-led coalition began to launch airstrikes on Yemen in March 2015, AQAP was able to seize and hold vast swathes of territory in the South and East of the country. This lasted for almost a year until April 2016, when UAE Special Forces moved in.

However, it would be a mistake to imagine that AQAP has been defeated. During 2015, as Yemen’s Houthi rebels advanced and coalition bombs rained down on the West side of Yemen, AQAP was able to position its de facto ‘state’ as a haven of stability in the East.

Operating out of the port city of Mukalla, it amassed significant financial resources and forged alliances with local militias. It implemented community development projects to shore up local support and adapted its global jihadist narratives to chime with local concerns.

While recent drone strikes and military operations have severely dented AQAP’s ability to operate openly, the kind of political and cultural capital it built up does not just melt away.

Nor can the ideas that underpin its appeal be bombed into oblivion. Quite the reverse: the ongoing conflict in Yemen means that the appeal of militant Islamist extremist groups like AQAP and, to a lesser extent IS, is likely to increase.

Although the current conflict began as a domestic battle for territory, power and resources, the involvement of Sunni Saudi Arabia (on the side of President Hadi) and Iran (providing some support to the Houthi rebels, most of whom adhere to an offshoot of Shi’ism) fuels the sectarian narratives promoted by militant jihad.

The ongoing conflict in Yemen means that the appeal of militant Islamist extremist groups like AQAP and, to a lesser extent IS, is likely to increase

If one adds to this poisonous climate the rugged topography of Yemen, the security vacuum left by an absentee government residing in Riyadh, the weakening of tribal social glue as internally displaced people head East, rampant smuggling networks buoyed by the war economy and a vast and porous coastline, what is the result? An ideal sanctuary for mujahidin fleeing the heartlands of IS in Syria and Iraq.

Although the number of Yemeni mujahidin returning from Syria and Iraq is unlikely to be high – after all, from 2015 they had their own battlefront and did not need to travel to the Islamic State to wage jihad – the worry is that those who do return will bring their comrades with them. This could lead to several potential alternative scenarios, three of which are as follows.

IS eclipse AQAP

First, if the number of IS mujahidin seeking sanctuary in Yemen turns out to be high, we could see IS start to rebuild in Yemen with the help of its existing local branches and by using the tribal contacts of returning Yemeni mujahidin, such that it ultimately eclipses AQAP.

IS confronts AQAP

Second, as IS numbers increase in Yemen, this could provoke more direct rivalry and confrontation between IS and AQAP. AQAP has been critical of IS’s premature announcement of a caliphate, its heavy-handed governance and its disregard for civilian casualties. Likewise, IS was highly critical of AQAP’s weak implementation of Shari’a law in Mukalla and the surrounding areas under its control until late April 2016.

IS fighters join AQAP

Third, we could see IS mujahidin start to integrate with AQAP, swelling its numbers and influence and possibly pushing it to become even more extreme. Also, if AQAP’s leading ideologues – who tend to take a more gradualist approach than IS – continue to be picked off successfully by drone strikes, that could drive its rank and file to adopt the more radical brand of militant jihad espoused by IS.

Which of these alternatives is most likely?

As for scenario one, given AQAP’s head-start in Yemen and the strong roots it has put down, it would be hard for IS point-blank to eclipse it.

Regarding scenario two, the animosity required to generate direct in-fighting among Yemen’s militant jihadist groups would likely be less strong than the solidarity found in battling adversity and the common goal of waging war against perceived Shi’ites (Houthi rebels) and the West. Hence, scenario three is perhaps the most likely.

As Yemen’s militant jihadists come under increasing military pressure from UAE-supported ground troops and Special Forces, they may increasingly bury their differences and join ranks such that we see the two groups start to blend.

Whatever the case, one thing is certain. The longer the current war is allowed to drag on and regional voices and identities in Yemen remain unheeded, the more fertile the breeding ground for militant jihad and the greater the challenge to counter-terrorism efforts.