WASHINGTON: The selection of a hard-line cleric as the new Taliban chief on Wednesday all but dashes US President Barack Obama's hopes for opening peace talks before he leaves office, one of his top foreign policy goals, current and former US defence and intelligence officials said.

The Taliban leadership council tapped Mullah Haybattulah Akhundzada, a conservative Islamic scholar from the group's stronghold in southern Afghanistan, to succeed Mullah Akhtar Mansour, four days after Mansour was killed in a US drone strike.

US officials had called Mansour a major impediment to peace talks, and some had expressed hope his death would eliminate an obstacle to peace negotiations between the Taliban and the government of Afghan President Ashraf Ghani.

Instead, some experts said, Akhundzada is likely to pursue aggressive attacks throughout the summer, intensifying the pressure on Obama to reconsider his plan to withdraw US military trainers and special forces and leave the decision on how to end America's longest war to his successor.

Late last year, Obama announced he would keep 9,800 US military personnel in Afghanistan through most of 2016. He added that US troops would be drawn down to 5,500 by the start of 2017.Obama has made extracting the United States from its 15-year war in Afghanistan a top priority, unsuccessfully pursuing efforts to bring the Taliban into talks with successive Afghan governments.

"Prospects for the Afghan peace process remain poor. The Taliban leadership, including the new commander, Mullah Akhundzada, believe military victory is only a matter of time," said Bruce Riedel, a Brookings Institution expert and former CIA officer who headed Obama's first Afghanistan policy review.

Riedel said Pakistan's powerful Inter-Services Intelligence agency also believed that the Taliban, which ruled Afghanistan for five years before their ouster in a US-led invasion in 2001, could win a military victory.

"The war is entering a more violent phase," he added, his prediction punctuated by a suicide bombing in Kabul that killed 11 people shortly after Akhundzada's selection was announced.

TROOP PLAN UNDER REVIEW

Confronted with Taliban gains, a weak Kabul government and the emergence of an Islamic State branch, the top US commander in Afghanistan is reviewing the withdrawal plan and is expected to complete his findings within a month.

The administration remains committed to its strategy of pressing for peace talks while providing funds and military advice, training and equipment to Afghan forces, said Defense Secretary Ash Carter, who indicated the US troop drawdown would resume.

The Taliban should realize "that they cannot win, that the Afghan security forces aided by us are going to be stronger than them and are going to be able to defend the state of Afghanistan and the government of national unity there, and therefore that the alternative to coming across and making peace with the government is their certain defeat on the battlefield," Carter said on Wednesday in Rhode Island.

But current and former US government experts and independent analysts said they saw little chance of that happening, with one US defence official noting the Taliban announcement of Akhundzada's accession made no mention of negotiations.

'WHAT HAVE THEY BEEN SMOKING?'

“Whenever I hear anyone in the administration talking about the prospects for peace negotiations or how killing Mullah Mansour could improve them, I have to ask what they’ve been smoking," a US military officer with extensive experience in Afghanistan, said on condition of anonymity.

"Regardless of who leads them, the Taliban have zero incentive to negotiate on their determination to restore their brand of Islamic rule."

He and other US military and intelligence officials pointed out that the Taliban had been making steady battlefield gains against Afghan security forces, who have been suffering high casualty rates.

Moreover, the coalition government brokered by the United States between Ghani and Abdullah Abdullah, his former rival and now the country's chief executive, is riddled by disputes and deeply unpopular.

The insurgents have little reason to trust the coalition government or Obama's successor, who takes office in January, to keep any agreement, said a US official with experience in Afghanistan.