Evan Perkoski and Alec Worsnop clear up an important misconception:
[C]ontrary to many media reports, ISIS is not a splinter group of AQ. ISIS wasn’t founded by or ever directly a part of AQ; rather, they were affiliates, two groups with close bonds, with one pledging loyalty to the other though at all times maintaining autonomy. This is an important distinction since labeling ISIS a splinter implies AQ factionalism that in reality never existed. Instead, ISIS’s links with AQ, rather than signaling weakness or factionalism, have played a major role in their development by providing access to resources, strategic and tactical guidance, recruits, and an ideology that helped socialize and bind together individuals from disparate backgrounds.
Benjamin H. Friedman also rejects the comparison in terms of the threat ISIS poses (or rather doesn’t pose) to the US:
The idea that we need to fight ISIS because of its potential to use terrorism against the United States suffers similar flaws [to the logic of the Iraq War]. During the Iraq War, hawks constantly warned that leaving Iraq would allow terrorist havens to form there. Their mental model was 1990s Afghanistan. They ignored the fact that al Qaeda (the original group that attacked Americans) came from particular conflicts, rather than being some kind of plant that grew in failed states. And even in Afghanistan, the problem was more that the government — the Taliban — allied with al Qaeda, rather than the absence of government. And hawks forgot that U.S. gains in drones and surveillance technology since the 1990s had destroyed havens—now those were easy targets.
Today, we are repeatedly told that ISIS is more brutal than al Qaeda and thus a bigger danger to Americans. But that logic confuses an insurgency with a group focused on attacking Americans. ISIS is a nasty organization fond of terrorist violence, radical Islam, and Islamic caliphates, but not an obvious threat to Americans. Conflating morally noxious Islamists with those bent on killing Americans is one of the errors keeping us at endless war.
In fact, Barak Mendelsohn considers ISIS’s ascendency evidence of al-Qaeda’s decline:
[B]eyond raising ISIS’ profile, the terrorist group’s march through Iraq also diminishes al Qaeda’s. Al Qaeda’s greatest achievement was the 9/11 attacks, but that was 13 years ago. Many of today’s jihadis were young children at that time. Moreover, the attack on the United States was only supposed to be a means to an end: the establishment of an Islamic caliphate in the heart of the Middle East. Al Qaeda franchises did manage to gain (and then lose) some territory in Yemen, Somalia, and northern Mali. But these territories are smaller in size and significance than what al Qaeda wanted — and what ISIS controls today. Although al Qaeda may have started the march toward the reestablishment of the Caliphate, it is ISIS that seems to be realizing it. …
Al Qaeda’s appeal relative to ISIS’ is greater when questions of how to run a territory populated by Sunni Muslims who do not subscribe to the Salafi-jihadi radical interpretation of Islam take center stage. When the front stabilizes and the intensity of the fight subsides, such questions will return and the inherent weakness of ISIS will resurface. ISIS is an extremely capable force, but its battle achievements do not make it any more appealing as a government.
The question is whether we can muster the patience and restraint to see it blow itself out.