The most senior military officer in the United States has said they will 'hunt down and kill' al-Qaeda's new leader Ayman Al-Zawahiri - just as it did Osama bin Laden.
It emerged yesterday that long-serving number two Al-Zawahiri had taken over as head of the group.
He had vowed earlier this month to press ahead with its campaign against the US and its allies.
Chairman of the Joint Chiefs of Staff, Admiral Mike Mullen, said he was not surprised by the choice of the Egyptian militant to succeed Bin Laden.
Mr Mullen also made it clear that Al-Zawahiri remained high on the US list of hunted militants.
'He and his organisation still threaten us. And as we did seek to capture and kill - and succeed in killing - Bin Laden, we certainly will do the same thing with Zawahiri,' he said.
US Defence Secretary Robert Gates said the development showed that al-Qaeda was still out there and needed to be pursued.
He said Al-Zawahiri does not have the 'peculiar charisma' and operational experience of Bin Laden, who was killed by US forces last month.
'We should be mindful that…al-Qaeda seeks to perpetuate itself, seeks to find replacements to those that have been killed and remains committed to the agenda that Bin Laden put before them,' Mr Gates told reporters.
'So I think…it is a reminder that they are still out there and we still need to keep after them,' he said.
Al-Zawahiri's whereabouts are unknown, although he has long been thought to be hiding along the border between Afghanistan and Pakistan.
The US is offering a $25m reward for any information leading to his capture or conviction.
