An image grab taken from a propaganda video released on July 5, 2014 by Al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. Baghdadi, the self-proclaimed caliph of the brutal jihadist Islamic State (IS) group that has seized large chunks of Iraq and Syria, made the AFP shortlist of most influential people of 2014. AFP PHOTO / HO / AL-FURQAN MEDIA
PHOTO: AL-FURQAN MEDIA/AFP/Getty Images
An image grab taken from a propaganda video released on July 5, 2014 by Al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. Baghdadi, the self-proclaimed caliph of the brutal jihadist Islamic State (IS) group that has seized large chunks of Iraq and Syria, made the AFP shortlist of most influential people of 2014. AFP PHOTO / HO / AL-FURQAN MEDIA
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An image grab taken from a propaganda video released on July 5, 2014 by Al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. Baghdadi, the self-proclaimed caliph of the brutal jihadist Islamic State (IS) group that has seized large chunks of Iraq and Syria, made the AFP shortlist of most influential people of 2014. AFP PHOTO / HO / AL-FURQAN MEDIA
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An image grab taken from a propaganda video released on July 5, 2014 by Al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. Baghdadi, the self-proclaimed caliph of the brutal jihadist Islamic State (IS) group that has seized large chunks of Iraq and Syria, made the AFP shortlist of most influential people of 2014. AFP PHOTO / HO / AL-FURQAN MEDIA
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An image grab taken from a propaganda video released on July 5, 2014 by Al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. Baghdadi, the self-proclaimed caliph of the brutal jihadist Islamic State (IS) group that has seized large chunks of Iraq and Syria, made the AFP shortlist of most influential people of 2014. AFP PHOTO / HO / AL-FURQAN MEDIA
PHOTO: AL-FURQAN MEDIA/AFP/Getty Images
An image grab taken from a propaganda video released on July 5, 2014 by Al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. Baghdadi, the self-proclaimed caliph of the brutal jihadist Islamic State (IS) group that has seized large chunks of Iraq and Syria, made the AFP shortlist of most influential people of 2014. AFP PHOTO / HO / AL-FURQAN MEDIA
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An image grab taken from a propaganda video released on July 5, 2014 by Al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. Baghdadi, the self-proclaimed caliph of the brutal jihadist Islamic State (IS) group that has seized large chunks of Iraq and Syria, made the AFP shortlist of most influential people of 2014. AFP PHOTO / HO / AL-FURQAN MEDIA
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An image grab taken from a propaganda video released on July 5, 2014 by Al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. Baghdadi, the self-proclaimed caliph of the brutal jihadist Islamic State (IS) group that has seized large chunks of Iraq and Syria, made the AFP shortlist of most influential people of 2014. AFP PHOTO / HO / AL-FURQAN MEDIA
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(FILES) This image grab taken from a propaganda video released on July 5, 2014 by al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group, Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. 
The Russian army on June 16, 2017 said it hit Islamic State leaders in an airstrike in Syria last month and was seeking to verify whether IS chief Abu Bakr al-Baghdadi had been killed. In a statement, the army said Sukhoi warplanes carried out a 10-minute night-time strike on May 28 at a location near Raqa, where IS leaders had gathered to plan a pullout by militants from the group
(FILES) This image grab taken from a propaganda video released on July 5, 2014 by al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group, Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. The Russian army on June 16, 2017 said it hit Islamic State leaders in an airstrike in Syria last month and was seeking to verify whether IS chief Abu Bakr al-Baghdadi had been killed. In a statement, the army said Sukhoi warplanes carried out a 10-minute night-time strike on May 28 at a location near Raqa, where IS leaders had gathered to plan a pullout by militants from the group's stronghold. / AFP PHOTO / AL-FURQAN MEDIA / --/AFP/Getty Images
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An image grab taken from a propaganda video released on July 5, 2014 by al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group, Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. Baghdadi, who on June 29 proclaimed a "caliphate" straddling Syria and Iraq, purportedly ordered all Muslims to obey him in the video released on social media.
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An image grab taken from a propaganda video released on July 5, 2014 by al-Furqan Media allegedly shows the leader of the Islamic State (IS) jihadist group, Abu Bakr al-Baghdadi, aka Caliph Ibrahim, adressing Muslim worshippers at a mosque in the militant-held northern Iraqi city of Mosul. Baghdadi, who on June 29 proclaimed a "caliphate" straddling Syria and Iraq, purportedly ordered all Muslims to obey him in the video released on social media.
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Story highlights

The Department of State's initial reward offer was $10 million

ISIS, under al-Baghdadi, has grabbed swaths of territory in Iraq and Syria

(CNN) —  

The United States is offering $25 million for information leading to the capture of ISIS leader Abu Bakr al-Baghdadi.

The Department of State released a statement Friday announcing the $25 million dollar reward for the self proclaimed caliph of the Islamic State in Iraq and Syria – more than doubling the reward announced previously.

“The threat that al-Baghdadi poses has increased significantly since the Department of State’s initial $10 million reward offer for information leading to his location, arrest, or conviction was announced in 2011,” the department’s Rewards for Justice Program said on its website.

Under al-Baghdadi, ISIS grabbed swaths of territory in Iraq and Syria – earning a reputation for unparallelled brutality.

Officials have long described al-Baghdadi as enemy No. 1 in the fight against the militant group, and speculation has swirled over his whereabouts.

Though al-Baghdadi has been elusive, he has spoken out occasionally in videos and audio messages.

In October 2015, Iraq’s military claimed its air force had struck a convoy in western Anbar province that included a vehicle carrying al-Baghdadi. For weeks, reports circulated that he was seriously injured in the airstrike.

Those reports have since been disputed by US officials.

CNN’s Joe Sutton and Catherine Shoichet contributed to this report.