Pakistan's Taliban have named Mullah Fazlullah as their new leader, after the death of Hakimullah Mehsud in a drone attack.Mullah Fazlullah is a particularly hardline commander whose men shot the schoolgirl activist Malala Yousafzai.
Mehsud was killed when missiles struck his vehicle in the North Waziristan region on 1 November.
The government had been trying to set up peace talks, but the new leader has already rejected the initiative.
The BBC's Richard Galpin in Islamabad says the Taliban have indicated that Mullah Fazlullah wants revenge for the killing of Mehsud.
A Taliban spokesman told the BBC the militants would target the military and the governing party.
AnalysisThe choice of Mullah Fazlullah as the new head of the Pakistani Taliban (TTP) is unlikely to please many Pakistanis. He was among the TTP's more vocal opponents of talks with Islamabad, so the group appears set to continue on the path of violence.
Mullah Fazlullah led the bloody occupation of the Swat Valley in 2008-09, and pioneered a violent campaign against polio vaccination.
Since his eviction from Swat in an army operation in 2009, he has moved to north-eastern Afghanistan from where he has launched several attacks against the Pakistani military, including one in September that killed an army general. He also said he was behind the assassination attempt on education activist Malala Yousafzai last year.
But he starts out with two major disadvantages - he is not based in Pakistan and he is not a native of the Waziristan tribal region, the main militant sanctuary. Many expect him to face problems in controlling the disparate, and at times fractious groups within the TTP, the bulk of them locals from Waziristan.
The Mehsud killing had angered the Pakistani government. Interior Minister Chaudry Nisar Ali Khan said that the drone strike was "not just the killing of one person, it's the death of all peace efforts".Mehsud clan The announcement of the new leader was made by the Taliban's caretaker leader Asmatullah Shaheen at a news conference at an undisclosed location.
When the news was announced, there was reportedly heavy celebratory gunfire in the area around Miranshah, the main town in the tribal area of North Waziristan.
Mullah Fazlullah led a brutal campaign in Swat between 2008 and 2009, enforcing hardline Islamic law, that included burning schools, and public floggings and beheadings.
A military operation was launched to retake the area.
Mullah Fazlullah fled over the border into Afghanistan but Islamabad says he has continued to orchestrate attacks in Pakistan.
He was accused of being behind a roadside bomb in September that killed Maj Gen Sanaullah Niazi, the top commander in Swat, along with two other military personnel.
Mullah Fazlullah was known for his radio broadcasts calling for strict Islamic laws and earning him the nickname "Mullah Radio".
The shooting of Malala Yousafzai in October 2012 sparked outrage in Pakistan and across the globe.
- Leader of Taliban in Swat in north-west Pakistan
- Ousted from Swat by troops in 2009 - now based on Afghanistan-Pakistan border
- First Pakistan Taliban leader not from tribal areas - all were from Waziristan so far
- His fighters shot schoolgirl activist Malala Yousafzai
- Known as Mullah Radio for his fiery broadcasts
The teenager had spoken out against the Taliban's restrictions on girls' education.She was airlifted to the UK for hospital treatment and now lives in Birmingham with her family.
This year Malala, now 16, addressed the UN General Assembly and won the European Union's Sakharov human rights prize.
Prior to the latest Taliban announcement, the BBC's M Ilyas Khan in Islamabad said that Mullah Fazlullah was not a member of the Mehsud clan and, if appointed, would face a challenge to control the Mehsud fighters, who make up the bulk of the Taliban's manpower.
The Taliban's ruling council took seven days to reach a decision.
Prime Minister Nawaz Sharif had come to power in May pledging a negotiated settlement to the insurgency, but militant attacks continued.
The government said a delegation had been due to fly to North Waziristan to discuss peace talks with Hakimullah Mehsud but he was killed in the drone strike the day before.
There had been some hope a new leader of the Taliban would be more open to the peace initiative.
Regional Taliban commander Khan Said Sajna, said to favour such a move, had been touted as a favourite before the latest announcement.