US Secretary of State John Kerry said Afghan Taliban leader Mullah Akhtar Mansour posed a "continuing imminent threat" to US personnel in Afghanistan and to Afghans, and was a threat to peace.
His comments come as the senior Taliban commander confirmed on Sunday morning that he had been killed in a US drone strike.
This action sends a clear message to the world that we will continue to stand with our Afghan partners as they work to build a more stable, united, secure and prosperous Afghanistan.
Peace is what we want. Mansour was a threat to that effort and to bringing an end to the violence and suffering people of Afghanistan have endured for so many years now. He was also directly opposed to the peace negotiation and to the reconciliation process.
Afghan Taliban leader Akhtar Mansour has been killed in a US drone strike, the senior Taliban commander has confirmed.
BREAKING: Senior Taliban commander confirms death of leader Mullah Akhtar Mansour in US drone strike.
The news comes after a US official said on Saturday that Akhtar Mansour was "likely to have been killed" along with another combatant in a drone strike ordered by Barack Obama
Multiple drones targeted the men as they travelled in a vehicle in a remote area along the Pakistan-Afghanistan border, near to the town of Ahmad Wal, the official - speaking on the condition of anonymity - said.
US officials have said that Afghan Taliban leader Mansour is "likely" to have been killed in a President Obama-authorised drone strike.Read the full story ›
The Taliban have claimed responsibility for a suicide attack on restaurant in Kabul that killed a 12-year-old boy and left more than a dozen people wounded, according to officials.
The bombing on Friday is the latest in a series of suicide attacks in the Afghan capital and targeted "Le Jardin", a restaurant popular with foreigners.
A police official said five people had been wounded in the blast, although a Taliban Twitter account said many "invaders" had been wounded or killed.
At the scene, large numbers of police and security force personnel blocked off the site, which was partially illuminated by flames from the explosion.
White House officials said that the US intelligence community has confirmed the death of Afghan Taliban leader Mullah Omar.Read the full story ›
The Afghan Taliban have appointed a new leader after the death of Mullah Omar.
Akhtar Mohammad Mansour will succeed one-eyed Omar, who had not been seen since 2001.
News of Omar's death was confirmed yesterday but it is thought he died more than two years ago.
Omar went into hiding after his government was forced from power by the US-led Coalition following the 9/11 attacks in the USA.
The White House has said it believes reports of Taliban leader Mullah Omar's death are 'credible'.
Earlier this evening the presidential palace in Kabul issued a statement stating that 'based on credible information' it was able to confirm Omar's death.
The Afghanistan Government is convinced that Taliban leader Mullah Mohammad Omar died two years ago and has called on all opposition parties to embrace new peace talks.
A statement from the presidential palace in kabul said: "The government ... based on credible information, confirms that Mullah Mohammad Omar, leader of the Taliban died in April 2013 in Pakistan."
"The government of Afghanistan believes that grounds for the Afghan peace talks are more paved now than before, and thus calls on all armed opposition groups to seize the opportunity and join the peace process."
The Taliban's leader Mullah Mohammad Omar died two years ago in a Pakistani hospital, Afghanistan's intelligence agency has claimed.
The statement by National Directorate of Security spokesman Hasib Sediqi came after the Afghan government said it was investigating reports of Omar's death, just days ahead of an expected second round of peace talks with the Taliban.
The NDS has previously said privately that its intelligence indicated Omar was dead, but it has not provided proof.
A former Taliban minister has told ITV News that Mullah Mohammad Omar is dead.
He said Omar died more than two years ago from a disease which was possibly tuberculosis and is buried in Afghanistan, close to the border with Pakistan.