Powerful Al Qaeda Group Slams Door on ISIS’s Leader

— -- Al Qaeda's most potent affiliate, the Yemeni branch of the terror group, today strongly rejected the Islamic "caliphate" in Syria and Iraq declared by ISIS leader Abu Bakr al-Baghdadi, in an announcement that terrorism experts said is good news for the West.

Harith bin Ghazi al-Nadhari, a top Shariah (Muslim law) official from al Qaeda in the Arabian Peninsula (AQAP), slammed the door on al-Baghdadi, saying they were "surprised" in June when the former al Qaeda-Iraq leader declared a "caliphate" stretching from northern Syria across large portions of Iraq and anointed himself "caliph."

"We do not see the authenticity of the establishment of such a Caliphate, nor what follows it of consequences," al-Nadhari said in a 28-minute video released by Yemen's AQAP today.

He referred to al-Baghdadi and his fighters in ISIS as "brothers" but said declaring a caliphate improperly has led to rifts beyond the bloody falling out of ISIS in Syria with core al Qaeda's leadership in Pakistan led by Ayman al-Zawahiri, Osama bin Laden’s replacement, and al Qaeda’s Syria affiliate, Jabhat al-Nusra. Al-Nadhari cited infighting among other jihadi groups in Africa, Asia and the Middle East and strongly affirmed AQAP's loyalty remains to Zawahiri and Taliban leader Mullah Omar, despite some groups pledging oaths of "bayat" to al-Baghdadi.

"I think it's pretty significant. It underscores the depth of the rift between ISIS and al Qaeda and that they're not going to align anytime soon," said Matthew Olsen, an ABC News contributor who served for three years as director of the U.S. National Counterterrorism Center.

He said the fracture among the two most lethal Islamist terror organizations is better than them joining forces against the West.

"Al Qaeda and the Islamic State [ISIS] are still potent in their own right. But they really are at odds with each other," Olsen said.

The AQAP message likely was approved by Nasir al-Wuhayshi, its top leader and Zawahiri's potential heir to core al Qaeda. It came as a response to al-Baghdadi's latest audio speech on Nov. 13, in which he boasted of the pledges of loyalty from a slew of jihadi groups.

"It's further proof that al Qaeda and the Islamic State don't work together," said Rita Katz, director of the private research firm SITE Intelligence Group, who provided a translation of the al-Nadhari speech. She said jihadis reacted angrily to the AQAP message.

"It is important that it came from one of AQAP's top Shariah officials, al-Nadhari, as the argument about the legitimacy of the Caliphate is a religious one. It is more appropriate that such rejection comes from al-Nadhari, a recognized Shariah scholar, and not from Wuhayshi," Katz told ABC News.

"Aside from keeping Wuhayshi above the fray, having their top Shariah official make the statement is also likely a way to highlight the fact that most serious jihadi scholars have come down firmly against ISIS," added terrorism expert J.M. Berger, co-author of a forthcoming book on ISIS's rise.

The announcement comes after months of anticipation after ISIS swept across Iraq in a blitz that caught the Obama administration off guard.

For months, AQAP's messages on Iraq and Syria have avoided taking sides, as many Yemeni fighters joined the estimated 16,000 foreign jihadis who have fallen in with ISIS in the region between Iraq and Syria they call "al Sham." Instead, the Yemeni terror group -- which has attempted at least four air attacks on the U.S. homeland since 2009 using undetectable bombs smuggled aboard passenger and cargo jets -- had repeatedly called on mujahideen fighters there to end their bloody infighting and focus on America and its "apostate" allies.

"We hold our brothers in the Islamic State responsible for all the consequences of these interpretations and dangerous steps [and] weakening the strength of the mujahideen, which is an inevitable result of fighting," AQAP's al-Nadhari said in the message on Friday.