PARIS (AFP) - To the uninitiated, Al-Qaeda and the Islamic State in Iraq and Syria (ISIS) group may be pursuing the same long-term goal of spreading Islamic law through territorial expansion and deadly violence.
But actually, their ideology and methods differ so fundamentally that they are increasingly turning on each other.
Last month, ISIS in West Africa (Iswap) released a video showing its men butchering fighters presented as members of the JNIM, an Al-Qaeda franchise, in Mali.
Fifty-two were killed.
According to Professor Mohammed Hafez at the Naval Postgraduate School in Monterey, California, internecine fighting has claimed the lives of some 300 Islamists in West Africa's Sahel region since July alone.
The reasons for the fighting range from control of territory or profitable trafficking corridors to filling power vacuums left behind when local leaders are killed.
"The civil war raging between global jihadis is intensifying," said Prof Hafez.
"These duelling factions have failed to overcome the challenge of fragmentation under the stress of conflict and territorial retreat," he wrote in the journal CTC Sentinel of the US Military Academy's Combating Terrorism Centre.
"They turned their attention away from near and far enemies and instead prioritised fighting the nearest enemy of all - each other."
ISIS arose from the ashes of an Al-Qaeda offshoot, Al-Qaeda in Iraq (AQI), largely decimated by US-led forces backed by local militias in the mid 2000s.
HEARTS AND MINDS
But ISIS immediately took a different course to Al-Qaeda - until then the West's public enemy No. 1 because of the 9/11 attacks in the US.
Whereas Al-Qaeda views the destruction of the West as a prerequisite for the establishment of an Islamic state, ISIS set out to establish a caliphate in "liberated territories" from where to launch its war of conquest, geopolitical researcher Nathanael Ponticelli wrote in the journal of the French Institute for International and Strategic Affairs (IRIS).
According to Prof Hafez, Al-Qaeda has sought to position itself as an "inclusive, pragmatic, and populist pan-Islamist movement" whereas ISIS represents "an exclusive, uncompromising, and puritanical vision of jihadism".
ISIS claims the exclusive legitimacy to punish "takfirs", Muslims considered to have strayed from the teachings.
"Whereas Al-Qaeda and other Islamists seek to work hand-in-hand with their beleaguered populations in order to win their hearts and minds, the Islamic State cares little about populism and instead advances an exclusive, vanguardist vision that seeks to mould hearts and minds through the divine imperative to command the good and forbid vice," said Prof Hafez.
In April, ISIS issued a 52-minute video pointing out what it says are instances of Al-Qaeda's deviance from scripture.
"The self-declared caliphate has developed a significant institutional hatred for Al-Qaeda," said Mr Thomas Joscelyn of The Foundation for Defence of Democracies.
"It is always possible that some factions within each group are currently working together, or they will do so in the future. But the video indicates that a grand reconciliation between the two jihadist rivals is unlikely in the near future."
NO SHORTAGE OF FIGHTERS
But, say observers, the Western world should not take comfort in the two Islamist groups being at each other's throats.
A lot can get trampled in their battle for supremacy, territory, followers and media attention, they warn.
"Since 9/11, the problem of violent jihadis has grown in scale, scope, and violent magnitude - all this despite being divided and pursued by a super power, multinational coalitions, and local governments," wrote Prof Hafez.
"Whereas in the past the international community was dealing with one global jihadi movement headquartered in Afghanistan, today there are two with branches that span several regions and countries."
Furthermore, the Islamists have proven they can "plan operations and fight their adversaries even as they are killing each other", said Prof Hafez.
For Mr Elie Tenenbaum, a researcher at the French Institute of International Relations (IFRI), the two groups are seeking to outdo each other - and neither is likely to run out of fighters.
"By fighting, the groups consolidate their domination and even conquer new territories," he told AFP.