The Islamic State terrorist group on Thursday confirmed the death of its leader, Abu Bakr al-Baghdadi, and announced his successor: Ibrahim al-Hashemi al-Qurayshi.

A top researcher on ISIS at Swansea University, Aymenn al-Tamimi, said this name was unknown but could refer to a senior ISIS leader named Amir Muhammad Sa'id Abdal Rahman al-Mawla, who has gone under various aliases.

ISIS also confirmed that its spokesman, Abu al-Hassan al-Muhajir, was killed in a separate, subsequent US strike that was conducted after the Baghdadi raid.

A man identified as Abu Hamza al-Qurayshi is ISIS' new spokesman, according to Thursday's announcement.

Though ISIS no longer controls territory, analysts have warned that the terrorist group is far from defeated and still poses a threat.

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The Islamic State terrorist group on Thursday announced it had a new leader and confirmed the death of Abu Bakr al-Baghdadi, who blew himself up amid a US-led raid on a compound in Syria's Idlib province last weekend.

Al-Baghdadi's successor is Ibrahim al-Hashemi al-Qurayshi, according to Site Intel Group, which tracks the online activities of extremist groups like ISIS. This is a pseudonym, according to top analysts, and is meant to signal that the new leader is descended from the Qurayshi tribe of the Prophet Muhammad.

Al-Baghdadi also claimed to be descended from this tribe, a necessary qualification in ISIS' view for the caliph, or leader, of the Islamic world. ISIS is referring to al-Baghdadi's successor as the "caliph" as well.

The name Ibrahim al-Hashemi al-Qurayshi is largely unknown, but a top researcher on ISIS at Swansea University, Aymenn al-Tamimi, suggested to Reuters it could be Amir Muhammad Sa'id Abdal Rahman al-Mawla.

Al-Mawla, who has also been linked to the aliases Hajj Abdullah and Abdullah Qardash, had been named by the State Department as a "potential successor" to al-Baghdadi. According to a notice from the State Department's Rewards for Justice program, al-Mawla was a "religious scholar" in Al Qaeda in Iraq — the extremist group ISIS grew out of — and "steadily rose through the ranks to assume a senior leadership role for ISIS."

The notice also said al-Mawla "helped drive and justify the abduction, slaughter, and trafficking of the Yazidi religious minority in northwest Iraq and is believed to oversee some of the group's global terrorist operations."

ISIS on Thursday also confirmed that its spokesman, Abu al-Hassan al-Muhajir, was killed in a separate, subsequent US strike that was conducted after the Baghdadi raid. A man identified as Abu Hamza al-Qurayshi is ISIS' new spokesman, according to Thursday's announcement, which came via an audiotape that was released online.

This announcement came several days after President Donald Trump on Sunday spent nearly an hour speaking about the Baghdadi operation in a celebratory and self-congratulatory fashion.

Trump's remarks on the Baghdadi raid have sparked criticism, as the vivid details he provided seemingly revealed classified information. The president also made claims about the operation, including that the ISIS leader was "whimpering," that were said to have left US officials scratching their heads wondering where he got such info and even whether it was true.

Though ISIS no longer controls the large territory it once did, analysts have warned that it is far from defeated and still poses a threat.

ISIS' announcement on Thursday warned the US against rejoicing in al-Baghdadi's death.

"Beware vengeance (against) their nation and their brethren of infidels and apostates, and carrying out the will of the commander of the faithful in his last audio message, and getting closer to God with the blood of polytheists," an ISIS spokesman said in the tape, according a translation reported by Reuters.