The Islamic State on Thursday confirmed the death of its founder and leader Abu Bakr al-Baghdadi and announced a successor. The propaganda arm of ISIS also confirmed the death of another top ISIS official, its former spokesman.

In an audio message released through its central media operation, the group's new spokesman announced that Baghdadi's successor is a man named Abu Ibrahim al-Hashimi al-Quraishi. He is a figure largely unknown outside of ISIS circles and is hailed in the message as "emir of the believers" and "caliph" of the group's alleged caliphate.

In the announcement, both Baghdadi and former ISIS spokesman Abu al-Hassan al-Muhajir were praised as "martyrs."

The ISIS announcement came four days after President Trump told a nationally televised news conference that U.S. forces brought "the world's No. 1 terrorist leader to justice."

It also came less than 24 hours after the head of the U.S. Central Command, Gen. Kenneth "Frank" McKenzie Jr., released video from the raid in northwestern Syria that resulted in the death of Baghdadi and five other ISIS fighters.

McKenzie offered fresh details on the operation against Baghdadi and warned that U.S. officials are bracing for "some form of retribution attack."

"We're under no illusions that [ISIS is] going to go away just because we killed Baghdadi," McKenzie told reporters at a Wednesday briefing.

He added that ISIS may be "a little disjointed" for a period. "They will be dangerous. We suspect they will try some form of retribution attack, and we are postured and prepared for that," McKenzie said.

The U.S.-only assault force was transported for about an hour by helicopter from a staging base in Syria to Idlib province, he said, roughly 4 miles from the border with Turkey. ISIS fighters, who McKenzie said "demonstrated hostile intent against U.S. forces," were eliminated by two airstrikes from supporting U.S. helicopters.

From there, the U.S. forces surrounded Baghdadi's compound, urging those inside to exit. Those who did included 11 children, McKenzie said.

Once the assault was completed, U.S. forces retrieved documents and electronics from the compound, which he described as "substantial."

After departing, the military destroyed the compound in a precision strike to "ensure that it would not be a shrine or otherwise memorable in any way" McKenzie said, adding, "It looks pretty much like a parking lot with large potholes right now."

In all, he said, six ISIS fighters died inside the compound, four women and two men, including Baghdadi.

McKenzie reiterated Trump's recounting of the raid from Sunday, in which Baghdadi detonated a suicide vest, which collapsed the tunnel he retreated into. McKenzie said Baghdadi also killed two young children with him in the tunnel. Officials believe they were both "under 12." Originally, officials said three children had been killed with Baghdadi.

McKenzie also said Baghdadi may have shot at oncoming U.S. forces before detonating his suicide vest.

"We believe that Baghdadi may have actually fired from his hole in his last moments," McKenzie said.

McKenzie said he could not corroborate President Trump's description of Baghdadi "whimpering and crying" as he fled in the tunnel.

"I'm not able to confirm anything else about his last seconds," McKenzie said, adding, "I just can't confirm that one way or another."

McKenzie said the Defense Intelligence Agency was able to confirm identification of Baghdadi "beyond a shadow of a doubt." Using DNA samples retrieved from the tunnel and comparing them with samples taken when the ISIS leader was detained at Iraq's Camp Bucca prison in 2004 "produced a level of certainty that the remains belong to Baghdadi 1 in 104 septillion," said McKenzie.

Baghdadi's remains were buried at sea within 24 hours of his death, according to officials.

More details also emerged about the Belgian Malinois dog injured in the raid. He is a four-year veteran of the Special Operations Command and has participated in nearly 50 combat missions.

The dog was injured by live electrical cables inside the tunnel after Baghdadi blew himself up, Pentagon officials said. He has been returned to duty.

According to a tweet from President Trump on Thursday, the dog, named Conan, "will be leaving the Middle East for the White House sometime next week!"

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