Al Qaeda’s leader, Ayman al-Zawahiri, released a new audio recording on Sunday, in which he called for an Islamist alliance against Russia and the West, and said his organization was ready to work with its previously despised offshoot ISIS against those common foes.

“The Americans, Russians, Iranians, Alawites, and Hezbollah are coordinating their war against us. Are we not capable of stopping the fighting amongst ourselves so we can direct all our efforts against them?” said Zawahiri, as translated by Reuters.

The audio had previously appeared on YouTube but has since been taken down for violating the site’s terms of service.

“My mujahideen brothers in all places and of all groups… we face aggression from America, Europe, and Russia… so it’s up to us to stand together as one from East Turkestan to Morocco,” the terrorist leader continued.

This appears to be a significant strategic shift for al Qaeda, which has fought bloody battles against ISIS throughout the turmoil of the Syrian civil war. As Reuters notes, the previous audio communique from Zawahiri dismissed the Islamic State’s “caliphate” as illegitimate. Indeed, that message was widely interpreted as a declaration of war against the Islamic State, which Zawahiri accused of “sedition” against al Qaeda.

Israel National News notes that al Qaeda’s franchise in Syria, the Nusra Front, made a temporary alliance with ISIS several months ago, but the agreement seemed to fall apart in June, when ISIS jihadis beheaded several captives affiliated with al Qaeda.

If such an ISIS-al Qaeda alliance took shape, there would probably be a spirited disagreement about which terrorist masterminds were in charge. A great deal of ISIS’ terrorist activity and social-media activism has been designed to present it as the larger, stronger, more aggressive, more ideologically pure successor to an obsolete al Qaeda. On the other hand, al Qaeda has lately been marketing itself to Islamists as the “moderate” alternative to the lunatics of ISIS.

In fact, terrorism expert Greg Barton told Australia’s News.com the Islamic State’s disputed claim to have brought down a Russian airliner over Egypt this weekend could be seen as an attempt to upstage al Qaeda. “Al-Qaeda’s enduring claim to fame so far is 9/11 and a series of large scale terror attacks,” said Barton. “It’s entirely possible that striking the Egyptians, doing something more of the scale of al-Qaeda style attacks, would be in line with IS’s ambition.”

While it is sometimes difficult to establish the timing of Zawahiri’s messages, Reuters notes that this one contains references to Russian aggression in Syria, which would suggest it was recorded sometime after the Russian bombing campaign began on September 30.