The ISIS leader at the top of the U.S. kill list has died after being wounded in Syria, a U.S. military intelligence official told NBC News Tuesday.
Abu Muhammad al-Adnani was the terror group's No. 2 commander, its charismatic director of external operations and main propagandist.
He succumbed to injuries sustained in Al-Bab, a town 15 miles northeast of Aleppo and 20 miles from the Turkish border, the official said.
Turkish air forces have been operating in the area where al-Adnani was believed to have been wounded, but it's unclear which military forces killed him.
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The U.S. — which had put a $5 million bounty on al-Adnani's head — had him under surveillance, the official said. The U.S. has been providing intelligence on targets to Turkey under a program called "Nomad Shadow," the official said.
Defense Dept. officials on Tuesday evening said they are still gathering information on the outcome of an assault on al-Adnani's position.
"Today coalition forces conducted a precision strike near Al Bab, Syria, targeting Abu Muhammad Al-Adnani, one of [ISIS]'s most senior leaders. We are still assessing the results of the strike, but al-Adnani's removal from the battlefield would mark another significant blow to [ISIS]," said Pentagon spokesman Peter Cook in a statement.
"The U.S. military will continue to prioritize and relentlessly target [ISIS] leaders and external plotters in order to defend our homeland, our allies and our partners, while we continue to gather momentum in destroying [ISIS]'s parent tumor in Iraq and Syria and combat its metastases around the world," he added.
Al-Adnani is best known for issuing an edict for lone wolves to kill Westerners in September 2014.
"If you can kill a disbelieving American or European — especially the spiteful and filthy French — or an Australian, or a Canadian, or any other disbeliever from the disbelievers waging war, including the citizens of the countries that entered into a coalition against the Islamic State, then rely upon Allah, and kill him in any manner or way however it may be," he said.
"Smash his head with a rock, or slaughter him with a knife, or run him over with your car, or throw him down from a high place, or choke him, or poison him."
As NBC News reported in December, al-Adnani was the No. 1 name on the U.S. list of ISIS leaders it wanted to kill.
"There is a large amount of evidence suggesting that he was tremendously influential in terms of pushing individuals in Western countries to carry out homegrown terrorist attacks," said Evan Kohlmann of Flashpoint, an NBC terrorism analyst.
"He is one of the top figures in ISIS. He is very closely associated with ISIS terrorist operations abroad."
Al-Adnani was one of the first foreign fighters to oppose U.S. Coalition Forces in Iraq after he crossed the border from his native Syria in 2003.
He swore allegiance to Abu Musab al-Zarqawi, the Al Qaeda in Iraq leader later killed by U.S. fighter-bombers. He reportedly was captured in 2005 and taken into custody at a camp run by the U.S. military, but was freed in 2010.
After his release, he became the chief spokesman for ISIS, and by 2014 he had assumed a top operational role. The U.S. declared him a "specially designated global terrorist" in August 2014.
His death comes less than six months after two other top ISIS officials — finance minister Haji Iman and No. 3 Omar al-Shishani — were killed.
"This is a really big blow for ISIS," said Laith Alkhouri, co-founder of Flashpoint. "It's not going to be what breaks its back but it could break the morale of fighters who idealized him so much."