The Islamic State militant group announced a new leader Thursday to succeed Abu Bakr al-Baghdadi, who was killed in an American-led raid in Syria last weekend.

ISIS named Abu Ibrahim Hashimi al-Quraishi in a message posted by its official media wing, according to the security consulting firm and NBC News partner Flashpoint.

It was the first time ISIS had acknowledged the death of al-Baghdadi, as well as that of another senior figure named Abu Hassan al-Muhajir. President Donald Trump had identified al-Muhajir as al-Baghdadi's "number one replacement."

In an audio message released Thursday, the group called on fighters to rally around the new leader and threatened America, according to a translation provided by Flashpoint.

Trump said al-Baghdadi killed himself and three of his children, detonating a suicide vest as U.S. forces closed in after a "dangerous and daring" raid Saturday.

NBC News reported Thursday that al-Baghdadi was betrayed by a member of his inner circle who led American troops to his compound in northern Syria.

While al-Baghdadi's death constitutes a significant blow to the militant group, experts have warned that it will not necessarily spell an end to the violent extremists trying to reconstitute their self-declared caliphate.