ISIS issued a rare message purportedly from the group's elusive leader Thursday, the first sign in months of Abu Bakr al-Baghdadi amid speculation about his demise.
In the audio recording — released by ISIS' Al-Furqan Media arm — Baghdadi called on Muslims everywhere to take up arms and "march forth" to join his cause, saying his battle is not ISIS' "war alone" to fight. He describes ISIS as "merely the spearhead" in a broader battle and urges Muslims to march forth wherever they may be to join the caliphate, or Islamic State.
It was not immediately possible to verify the voice on the recording was Baghdadi, however security consulting firm and NBC News partner Flashpoint Intelligence said the audio appeared to be authentic.
In the message, Baghdadi refers to the current war in Yemen — signifying that the audio was recorded recently. The exact date of the recording is not known.
He stresses that the call to arms is not "out of weakness or incapability," saying that ISIS is "strong."
The message's release — a day after Iraq's military said it had killed ISIS' deputy leader — appears to be an attempt to put quash rumors that have swirled for months about Baghdadi's death or distance from the group's day-to-day operations. Analysts say the message may be designed to rebuff speculation about the organization's strength as it fights on a number of fronts. In recent weeks, ISIS has been locked in battle with Iraqi government and Shia militias inside western Iraq, and regime forces and rival militant groups inside Syria.
"The perception of momentum is important to the Islamic State. So it needs to carry on looking like it's successful," said Charlie Winter, a researcher with the London-based Quilliam Organization. "This speech is all about appealing to supporters: 'I'm alive we're making progress.'"
Baghdadi's last known public appearance was at a mosque in Mosul, Iraq in July 2014, where Baghdadi delivered an address declaring the establishment of a caliphate. That appearance — recorded and distributed as a video on jihadi websites — initially raised questions over whether Baghdadi would assume a more public presence, but the ISIS leader has kept a low profile since.
In November, ISIS released an audio recording purportedly from Baghdadi which promised"volcanoes of jihad" and dismissed the U.S. as "terrified" and meek. The recording — which purportedly featured the ISIS leader saying ISIS fighters would "never abandon" their cause — was released just days after reports emerged suggested Baghdadi had been critically wounded in an airstrike in Iraq.
That recording was widely considered to be a message from Baghdadi to make clear he was not hiding or dead.
Since then, there have been numerous reports about Baghdadi's possible death or injury — though none has been substantiated by NBC News. U.S. officials also have said repeatedly they cannot confirm the reports, including one in Britain's Guardian newspaper recently stating Baghdadi was"incapacitated" following an airstrike.
Born in Iraq's city of Samarra, Baghdadi has been portrayed in jihadi propaganda as an imam from a religious family descended from noble tribes, and a scholar and a poet with a Ph.D. from Baghdad's Islamic University, possibly in Arabic. He was held at the U.S. detention facility Camp Bucca in 2004 and after his release rose through the ranks of the Islamic State of Iraq — the terror successor to Abu Musab al-Zarqawi's al Qaeda in Iraq.
When the organization's leaders were killed in 2010, Baghdadi stepped into the void. Baghdadi — which is not his birth name — uses a host of aliases and is said to wear a bandana around his face to conceal his identity from everyone except a very tight inner circle that is thought to be comprised only of Iraqis.
When fighting in Syria intensified in the summer of 2011, Baghdadi saw an opportunity and opened a branch there and changed the name of his group to ISIS.
In a June 2013 audio recording, he vowed to erase Iraq's "Western-imposed border with Syria" and called on his followers to "tear apart" the governments in both countries.
The U.S. has offered $10 million for information leading to Baghdadi's capture.