Donald Trump says U.S. knows who new ringleader of Daesh is

President Donald Trump said Friday that the United States knows who the Daesh terror group's new leader is, as the United States vowed to keep "unrelenting" pressure on the extremists.

"ISIS [Daesh] has a new leader. We know exactly who he is!" Trump tweeted, less than a week after a US-led commando raid killed the group's leader Abu Bakr al-Baghdadi.

Daesh on Thursday confirmed Baghdadi's death and named his replacement as Abu Ibrahim al-Hashimi al-Quraishi.

However, little is known about Hashimi, whose name was seldom mentioned as a possible successor the multiple times that Baghdadi was falsely reported killed in recent years.

Nathan Sales, the State Department counterterrorism coordinator, provided no details on Hashimi when asked by reporters, saying only that the United States was "looking into the leader, his role, the organization where he came from."

"We will continue to subject that organization to unrelenting counterterrorism pressure using all the tools of national power," Sales said.

"We will dismantle the group regardless of who its leadership cadre is," he said.

Baghdadi, who led Daesh since 2014 and was the world's most wanted man, died in a US special forces raid in Syria's northwestern province of Idlib on Sunday.

Daesh also confirmed the killing in another raid the following day of the group's previous spokesman, Abu Hassan al-Muhajir.

The statement said the terror group's legislative and consultative body convened after the 48-year-old Iraqi-born Daesh chief's death and "agreed" on a replacement.

An Daesh spokesman denounced Trump as a "crazy old man" and warned that the group would avenge Baghdadi's death.