The head of US forces in Afghanistan says the Taleban are "desperate" and "dangerous" and could try to mount a high-profile attack soon.
Most of the Taleban organisation could collapse, says Barno
Lt Gen David Barno said much of the Taleban was close to collapse and would rejoin the Afghan political process.
But he said a hardcore of supporters would "grow more and more desperate to try to change the course of events".
The US has about 18,000 troops backing the Afghan government and tracking remnants of the Taleban and al-Qaeda.
Gen Barno said at a news conference in the capital, Kabul: "Terrorists here in Afghanistan want to reassert themselves and I expect that they will be looking here, over the next six to nine months or so, to stage some type of high-visibility attack."
The general did not say whether there was any information on specific targets.
"I think we must all remain realistic and clear-eyed with the understanding that the enemy is still dangerous," Gen Barno said.
But he added: "The diverging organisation that I see evolving over the next year or so [involves] much of the organisation, probably most of it, I think collapsing."
Change of tactics
The general pointed to the election of Hamid Karzai as president last October as a "strategic defeat" for the Taleban, which ruled Afghanistan until the regime collapsed in late 2001 following the arrival of US-led troops.
US-led forces and the Afghan government now face a huge logistical exercise to ensure the safety of parliamentary elections in September.
Gen Barno said some Taleban leaders were trying to "test the waters" to return to the political process.
However, Mawlavi Abdul Kabir, believed to be the number two in the Taleban after Mullah Mohammad Omar, said in a taped message to the Reuters agency there was no rift in the organisation and no talks with the US or Afghan governments.
He said the group was changing its tactics, saying it planned to train suicide bombers to carry out attacks.
"[This] is an easy way for us to have a longer-term war of attrition and would also not cost many lives for us," he said.
There was a lull in insurgent activity over the winter but there are signs the Taleban are now picking up their attacks.