Shoppers at the Westgate Mall in Nairobi who unfortunately found themselves besieged by al-Shabab militants last Saturday were witnesses to quite a peculiar scene. After storming the compound, the militants of the Somali al-Qaeda affiliate lined up their captives and started separating Muslims from non-Muslims, in what al-Shabab described in an email exchange Wednesday with The Associated Press as “a meticulous vetting process.” Witness accounts by survivors said they were asked to name the Prophet Muhammad’s mother. Those who passed the test were set free. Those who failed to provide the right answer (Amina) were gunned down.

Using this tactic to verify Muslims are not targeted is indeed unique, but this is not the first time jihadi militants are recorded being extra cautious of spilling innocent Muslims’ blood in their attacks. On September 18, one of the al-Qaeda affiliates in Syria, Jabhat al-Nusra, published online a video documenting a car bomb attack in a Syrian Army checkpoint, which took place September 4 at the entrance of the ancient Christian town of Ma’lula. The video depicts a vehicle approaching the checkpoint. The militant who drives the vehicle seemingly holds fire due to the presence of innocent civilians nearby. A caption that shows up at the bottom of the screen reads: “The jihadists are anxious for the lives of Muslims.” The driver allegedly warns these civilians to leave the area before a second vehicle laden with explosives reaches the checkpoint and blows up.

Other videos from Syria and Iraq from the past few years have also shown similar scenes in which jihadists had to withhold an attack or completely halt it due to the proximity of Muslim civilians. These acts are always accompanied with a massive PR campaign similar to the one described above. It is apparently very important for al-Qaeda to show it does its best not to kill Muslims.

It has a good reason to do so. Targeting Muslims in terrorist attacks is one of the main factors, if not the most important one, for the revulsion most Muslims feel for al-Qaeda. The numbers speak for themselves: an enlightening study by the Combating Terrorism Center at the U.S. Military Academy at West Point in New York from December 2009 revealed that al-Qaeda kills eight times more Muslims than non-Muslims. The study, which was based on claimed al-Qaeda attacks between 2004 and 2008, also showed that an overwhelming majority of 85% of the casualties during these years were Muslims.

In theory, al-Qaeda has developed over the years a suitable canon to hold back accusations on the religious field. The organization’s ideologists, headed by current leader Ayman al-Zawahiri and his slain deputy and chief theologian Abu Yahya al-Libi, have wiped the dust off a marginal and extremely controversial Islamic principle called Tatarus, which permits the killing of innocent Muslims under some circumstances when the enemy is using them as human shields. Even then, according to the Islamic exegesis, one has to weigh the benefits of such attack against the costs of shedding Muslims’ blood, and attack only if avoiding action would have grave repercussions for the entire Muslim Community. Al-Qaeda scholars have worked their way between some of these obscure definitions and tailored a modern interpretation of this principle to match their actions.

But there’s a huge gap between theory and practice, and al-Qaeda was soon to find out that playing the ‘religious justification’ card is not enough. Also, there was a growing unease from within the salafi-jihadi realm with the too-flexible interpretation of this principle by some al-Qaeda affiliates, most noteworthy of which was al-Qaeda in Iraq and its leader, the notorious Jordanian jihadist Abu Mussab al-Zarqawi. In 2005, the U.S. forces in Iraq intercepted a letter from Zawahiri to Zarqawi in which the former voiced his concern with the indiscriminate killing of Muslims in large scale attacks by the local al-Qaeda affiliate. In 2008, in an open speech he gave to members of al-Qaeda online forums, Zawahiri warned jihadists not to exaggerate in their use of Tatarus. Two weeks ago, the leader of al-Qaeda issued his first “General Guidelines for Jihad,” taking this call for restraint one step further by instructing jihadists to “generally avoid fighting or targeting those who have not raised arms against us” and “refrain from killing and fighting against non-combatant women and children.” The word Tatarus was not mentioned even once in Zawahiri’s guidelines, which may indicate that al-Qaeda has realized that insisting on playing this card does not serve the organization’s general interests and only further damages its reputation.

The evolution of al-Qaeda’s conception vis-à-vis the targeting and killing of innocent Muslim civilians in terrorist attacks shows that despite the public perception of a detached and intolerant organization, it is gradually becoming more aware and attentive to the needs of its target audience. It is also another testimony of al-Qaeda’s attempts to adjust to a post-Arab Spring environment, where the organization is striving to set foot in the door of Middle East societies and assume a leading position in the region’s politics.