Ayman al-Zawahiri, who took over as leader of al-Qaeda after the liquidation of Osama bin Laden, has released an audio message accusing ISIS leader and self-proclaimed “caliph” Abu Bakr al-Baghdadi of “sedition” and declaring war against the Islamic State.

ISIS, an offshoot of al-Qaeda once casually dismissed by President Barack Obama as its “junior varsity squad,” has far eclipsed its parent organization, carving out a durable terror state from chunks of Iraq and Syria. Baghdadi has declared his conquered territory to be the “caliphate,” the kingdom of Islam, with himself as the prophesied “caliph” who rightfully rules all true Muslims.

Almost everything ISIS does is saturated with this mythology. For example, its hideous magazine Dabiq is named after a town in Syria it controls, which is supposed to be the site of a final battle against the “crusaders” of the West, in which Muslims will prevail and usher in the end of history.

This is a major doctrinal sticking point with al-Zawahiri, who recently swore allegiance to the new leader of the Taliban, Mullah Akhtar, and has previously recognized Akhtar’s late predecessor Mullah Omar as the “caliph.” ISIS has been trying to establish a foothold in Afghanistan, and has been fighting against both Taliban and al-Qaeda forces there.

ABC News reports that in the audio clip, Zawahiri discusses the fighting between ISIS jihadis and al-Qaeda’s franchise in Syria, Jabhat al-Nusra. “We preferred to respond with as little as possible, out of our concern to extinguish the fire of sedition,” says the al-Qaeda leader, “but Abu Bakr al-Baghdadi and his brothers did not leave us a choice, for they have demanded that all the mujahideen reject their confirmed pledges of allegiance, and to pledge allegiance to them for what they claim of a caliphate.”

He went on to describe Baghdadi’s declaration as a “surprise,” and something the ISIS leader did “without consulting the Muslims.”

ABC News quotes National Counter-Terrorism Center Director Matthew Olsen describing the new Zawahiri audio as an “interesting” development.

“Zawahiri until now has not been willing to openly condemn Baghdadi and ISIS. It highlights how deep the division is between al Qaeda leadership and ISIS. It suggests that the differences are irreconcilable,” he said, suggesting that U.S. intelligence operatives could take this opportunity to goad ISIS and al-Qaeda into more gunfights and assassinations.

Other intelligence analysts quoted by ABC agreed that the split between ISIS and al-Qaeda, and perhaps a growing divide within al-Qaeda itself, should be exploited. Nicholas Palarino of Georgetown University suggested “moderate Muslims need to exploit this rift,” taking the opportunity to spotlight the deficiencies and twisted theology of both ISIS and al-Qaeda to persuadable Muslims around the world.

However, it should be noted that while Zawahiri had strong words for Baghdadi, he reiterated the willingness of al-Qaeda to fight alongside ISIS against common enemies such as the United States. “We don’t recognize this caliphate,” Zawahiri said, but added that “despite the big mistakes [of Islamic State], if I were in Iraq or Syria I would cooperate with them in killing the Crusaders and secularists and Shi’ites even though I don’t recognize the legitimacy of their state, because the matter is bigger than that.”

Also, al-Qaeda’s value as a weapon against ISIS may be limited, because bin Laden’s old gang is not in good shape these days. The UK Guardian quotes “two of al-Qaeda’s most important spiritual leaders” declaring that “the terror group is no longer a functioning organization after being ripped apart by ISIS.” They spoke of Zawahiri as being “cut off from his commanders and keeping the group afloat through little more than appeals to loyalty.”

The Guardian further cited Jordanian officials who judged al-Qaeda “has been drained of recruits and money after losing territory and prestige to its former subordinate division.”

The best news for al-Qaeda recently is the failure of ISIS to win the allegiance of al-Shabaab in Somalia, which appears to remain firmly in al-Qaeda’s camp. The Long War Journal notes that Zawahiri offers condolences for the death of al-Shabaab’s leader Ahmed Adbdi Godane, killed in a September 2014 U.S. air strike, and accepts the oath of allegiance from his successor in the new audio release.

ISIS themselves dismiss al-Qaeda as a “drowned entity” in the latest issue of Dabiq magazine. On the other hand, the Islamic State is still expanding, and coming close to a knockout punch against the Assad regime, having recently captured the last major Syrian oilfield.

Furthermore, it seems clear this audiotape from Zawahiri was recorded quite some time ago – at least eight months, by some estimations – because he speaks as if Mullah Omar was still alive. If that is true, it would mark a substantial degradation of Zawahiri’s communications ability, as he previously had little trouble publishing his pronouncements quickly.