Al-Qaeda has announced this week the death in Pakistan of one of its top operatives, the Egyptian known both as "Mustafa Abu al-Yazid" and "Sheikh Said al-Masri".
The announcement, attributed to "al-Qaeda General Command (Afghanistan)" was disseminated on Monday by al-Qaeda's usual media outlet, Al-Fajr Media Centre, and is assumed to be genuine.
Who was he?
Mustafa Abu al-Yazid, who was 54, was the key intermediary between al-Qaeda and the Afghan Taliban. He has been described as al-Qaeda's "number three" and the organisation's leader in Afghanistan.
US officials say he was one of al-Qaeda's founding members with direct access to both Osama Bin Laden and Dr Ayman al-Zawahiri, as well as the Taliban leader Mullah Omar.
Born in Egypt's Nile Delta in December 1955, he was imprisoned for three years for alleged links to the assassination of Egyptian President Anwar Sadat in 1981.
Like many other Egyptian Islamists he left his home country soon after his release to join "the Afghan Arabs" in Afghanistan.
When Osama Bin Laden moved to Sudan after Operation Desert Storm in 1991, he went with him. He then followed the al-Qaeda leader back to Afghanistan in 1996 to become the organisation's chief financial officer.
He is believed to have played a significant role in organising the finances for the September 2001 attacks on the US.
His appointment as head of al-Qaeda's Afghan operations was announced in 2007 and since then many of his statements have been posted on jihadist websites.
As recently as 26 April, he posted a message eulogising al-Qaeda's two top leaders in Iraq, who had been killed that month.
How was he killed?
Mr Yazid was killed in late May by a missile fired from a US-operated unmanned aerial vehicle (UAV) in Pakistan's North Waziristan tribal area.
The al-Qaeda statement says his wife and three children were killed with him and Pakistani officials say the missile strike took place near the town of Miran Shah.
The US authorities had been hunting him for some years and his death follows a number of similar missile strikes on key al-Qaeda operatives hiding in Pakistan's tribal areas.
What impact will this have?
There is no question that this is a setback for al-Qaeda's core leadership and its relations with the Afghan Taliban, but it is one which the organisation will have predicted and planned for.
Mr Yazid was not a combat commander. His skill lay in planning, organising and forging alliances, most notably between al-Qaeda and the Taliban.
He is one of the last big figures to have survived from al-Qaeda's formative early years, with nearly all the others having been killed or captured.
In a world where personal contacts, trust and connections count for everything his death will leave a temporary gap for global jihadists in the Afghanistan/Pakistan arena.
However, Western governments and their intelligence agencies have repeatedly underestimated al-Qaeda's resilience and its ability to swiftly recover from the loss of such key figures.
The early optimism of the President Bush years - that by "wrapping up" al-Qaeda's leadership, the movement could be broken and defeated - has been followed by a more realistic approach.
This acknowledges that jihadist leaders will be replaced and that their networks can regenerate themselves.
But the US government and its allies are hoping that by slow, steady attrition of such key figures, al-Qaeda's core leadership will be kept sufficiently off-balance to make it harder to plan and execute major attacks on the West such as the liquid bomb plot of 2006 and the London bombings of 2005.