The Afghan Taliban confirmed the death of leader Mullah Akhtar Mansour in a U.S. airstrike and named the group's chief justice as his replacement early Wednesday.
Haibatullah Akhundzada was elevated to the group's top position.
Akhundzada also served as a judge during the Taliban regime. After the group was routed by the U.S. invasion in 2001, he was made shadow chief justice.
Akhundzada, who Taliban sources say is around 60 years old, has issued religious edicts or "fatwas" justifying terrorist attacks against U.S. troops.
A senior Taliban source who spoke to NBC News on condition of anonymity said Akhundzada's hard-line views, including his opposition to peace talks with the Afghan government and the U.S., were popular among the militants.
"It seems we have Mullah Mohammad Omar back on the seat as he is similar to him in his policies," the source said, referring to former Taliban leader whose 2013 death was announced last year. "He is the true follower of Islam and never compromises on principles."
Mansour was killed Saturday in a U.S. airstrike in southwest Pakistan. On Tuesday, Pakistan's interior minister became the first public official in that country to speak out against the attack.
The "Americans have sabotaged the peace process," Chaudhry Nisar Ali Khan said at a press conference in Islamabad.
Pakistani authorities have been accused of sheltering and supporting some Taliban leaders — an accusation Islamabad denies. The insurgents have been fighting to overthrow the government in Kabul since 2001, when their own Islamist regime fell following the U.S. invasion triggered by the 9/11 attacks.
For its part, the Afghan government has said Mansour was an obstacle to any sort of peace process, which ground to a halt when he refused to participate in talks earlier this year.
In a statement, the Taliban confirmed Mansour's death.
"With heavy heart, but full belief in Allah's will, the Islamic Emirate of Afghanistan announces that the leader of the Islamic Emirate [Commander of the Faithful] Mullah Akhtar Mohammad Mansour was martyred in an American invading and evil forces' drone strike on Saturday," the statement said.
The Taliban also called on Muslims to mourn Mansour for three days.
When Akhundzada was appointed Mansour's deputy last year, he ran a large madrasa — or religious school — in Pakistan's lawless Balochistan province. Many of the Taliban's top commanders studied in the school and remained his students, sources within the group said.
The naming of Sarajuddin Haqqani, the operational commander of the dreaded and hyper-violent terror network of the same name, as Akhundzada's first deputy could be an indication of the direction the Taliban was headed. The Haqqanis, which one Western diplomat dubbed "the Kennedys of the Taliban movement," have been behind some of the most ferocious attacks against U.S. troops and local civilians in Afghanistan.
A senior Afghan security official warned that the leadership announcements could signal "a rise in violence and attacks in the coming days."
"Haibatullah will most likely be a figurehead, and the organization will be led by Haqqani," the source told NBC News on condition of anonymity because he was not authorized to speak to the media.
Mullah Mohammad Yaqoob, Mullah Omar's son, was named second deputy, Taliban spokesman told NBC News.
Mansour's killing presented the Taliban with its second leadership crisis since July — when the group revealed that Mullah Omar had died two years earlier.