How do the jihadist rebels generally conceive of jihad in the Syrian civil war?
One useful way to look into this question is to examine the Qur'anic verses pertaining to warfare cited in propaganda statements. In this context, one recurring verse is 22:39, which runs as follows: 'Permission [to fight] has been granted to those who are being fought, because they have been wronged. And verily is God able to grant them victory.'
For example, at the start of the final rebel offensive on Raqqah at the beginning of this month that successfully took the city out of the hands of Assad's forces, a video emerged on Youtube entitled 'Statement from Jabhat al-Nusrah [JAN] on the beginning of the battle to liberate Raqqah.' In this video, one can see three fighters from JAN – the al-Qa'ida-aligned jihadist group. The speaker begins the statement with citation of 22:39.
In a similar vein, at the end of last year, a battalion calling itself 'The Free Men of the Euphrates Battalion' invoked 22:39 at the opening of the announcement of its formation. In January of this year, a claimed police defector in Hama highlighted 22:39 in announcing his defection to Ahrar al-Sham, which has since merged with numerous other battalions to form a broad jihadist umbrella group that played a key role in the capture of Raqqah.
To be sure, 22:39 is also cited beyond jihadist circles, for it was notably invoked by the prominent Islamic scholar Mohammed Ali al-Sabouni- head of the Association of Syrian Scholars and a member of the Syrian National Coalition (opposition coalition-in-exile)- as a justification for taking up arms against the Assad regime.
Coming back to JAN (on whom I focus since it is considered the most hardline jihadist group), another Qur'anic quotation cited in their propaganda is 9:39, which states: 'Fight the polytheists altogether just as they fight you altogether.' This verse appeared at the beginning of a video released through the group's official channel, called 'The White Minaret.'
JAN's channel also released a video that begins with quotation from 4:75, which speaks of the need to fight in the cause of God for the oppressed who cry out for aid: a theme emphasized in the same video.
One could go on, but the point is that by citing all these verses, even JAN places an emphasis on what might be termed 'defensive jihad': that is, fighting in self-defense and in defense of one's fellow Muslim brethren in the face of a regime seen as waging war on Islam.
Indeed, the doctrine contrasts with 'offensive jihad', which is a concept that normally relies on a verse of the Qur'an quite different from the ones cited above: namely, 9:29. Modern al-Qa'ida theorists use this verse to argue that Muslims must conquer the world for Islam. Osama bin Laden himself made this aggressive approach clear in an essay stating that non-Muslims had three choices: conversion, subjugation, or death.
This kind of grandiose vision was duly taken up by al-Qa'ida-aligned jihadists fighting in places like Iraq and Mali, where their brutality towards the local populations helped to foster alienation.
In contrast, an emphasis on portraying the struggle against Assad as 'defensive jihad' means that providing protection and aid for local Muslim populations (see e.g. here and here)- or, to borrow a counter-insurgency phrase, 'winning hearts and minds'- has become a key part of jihadist strategy, whatever their wider ambitions might be.
This also means a more cautious approach to implementing strict Islamic law for fear that doing so hastily might provoke too much resentment. Thus, in JAN's case, it is not true, pace some rumors, that the group immediately forced women's clothing stores in Mayadeen to shut upon the announcement of a supposed 'Shari'a Committee for the Eastern Region' of Syria.
Indeed, much was made of a video showing a protest against JAN in Mayadeen, but it would appear the extent of the opposition was exaggerated. It is doubtful whether there were three straight days of protest against JAN as the Syrian Observatory on Human Rights claims. In any event, Mayadeen also saw counter-protests in favor of JAN (hat-tip: @Marwouantounsi).
On the other hand, in rebel-held areas of Aleppo, where JAN and other jihadist groups have had much more time to consolidate their presence, the impact of strict application of Islamic law is far more apparent through the full force of Shari'a courts- a phenomenon well documented in a recent New York Times report.
Even so, a hint of caution remains: recently a Shari'a-court affiliated with JAN arrested Dr. Othman Haj Othman- a popular member of Aleppo's unofficial opposition council and a doctor who devoted himself to treating injured protestors in the city. Othman's supposed 'crime' was to remove a JAN flag from the hospital he was working at. Yet Othman was released only a day later, likely as a result of the outrage the arrest triggered.
In short, the jihadist groups' approach of 'defensive jihad' entails a more gradualist outlook to implementing Shari'a, somewhat similar to the Muslim Brotherhood's conception of applying Islamic law through 'gradual action…step by step, in order to facilitate understanding, studying, acceptance and submission.'
Such an approach is also supported by prominent cleric Yusuf al-Qaradawi and is clearly seen in the Egyptian government's recent policies towards prohibition on alcohol.
Yet in the long-run, this strategy adopted by the main jihadist groups in Syria does not necessarily point to much more significant success than elsewhere. As Phillip Smyth notes, approximately 1000 militias could be operating on the ground at the moment, which speaks against the idea of any single faction or alliance of groups becoming dominant in the country, for rivalries between different rebel groups in such a situation- even among those that broadly share the same ideological outlook- are impossible to avoid.
Further, the end-result of a gradualist approach to applying strict Shari'a is the same as one of immediate implementation: namely, significant restrictions on civil and political liberties- particularly as regards minorities (especially the Alawites, frequently attacked in jihadist rhetoric as 'Nusayri apostates') and women- that will help to stir up at least some resentment.
To conclude, the picture is one of general chaos, with jihadist strongholds most likely to arise and endure in the north and east of Syria.