The American commander of coalition forces in Afghanistan says he expects to bring Osama Bin Laden to justice by the end of this year.
Barno: Al-Qaeda's leadership "must be destroyed"
Lieutenant-General David Barno said dealing with Bin Laden and ex-Taleban leader Mullah Omar was a top priority.
"The sands in the hourglass of all of the al-Qaeda senior leadership is running out," said General Barno.
He was speaking as Afghan interim President Hamid Karzai signed the country's new constitution into law.
General Barno commands about 11,000 mostly American troops in Afghanistan whose focus is combating al-Qaeda and members of the Taleban still operating in the south and east of the country.
In an exclusive interview with the BBC, he said the problem of Bin Laden and Mullah Mohammad Omar would be resolved this year.
Capturing Mullah Omar [L] and Bin Laden is a top priority, says Barno
"You can be assured that we're putting a renewed emphasis on closing this out and bringing these two individuals to justice, as well as the other senior leadership of that organisation.
"They represent a threat to the entire world and they need to be destroyed."
At least 500 people are estimated to have been killed in the past six months or so of fighting in Afghanistan.
There are continuing fears this insecurity will disrupt this summer's planned elections - polls that are supposed to follow today's adoption of the new constitution.
General Barno said he could provide the necessary security but criticised the United Nations for its planning of the elections.
He also signalled a more aggressive approach by US and coalition forces in tackling the drugs trade, which many now regard as one of the most significant threats to Afghanistan's transition to democracy.
Mr Karzai signed the country's new constitution in a ceremony on Monday at the foreign ministry in Kabul.
The document was agreed earlier this month at a grand assembly, or loya jirga, of regional representatives.