Bin Laden's death
America is rejoicing. George Bush promised Bin Laden - dead or alive. President Obama has delivered that promise and, crucially, before America marked the tenth anniversary of the 9/11 attacks.
Others are better placed than me to analyse what this means for Al-Qaeda and for events in the Arab world. The politics of this news, though, seem pretty clear.
Obama was elected to end the wars in Iraq and Afghanistan. For many Americans the loss of life there was justified only as a response to the attacks on New York and Washington on 9/11. The talk of spreading freedom and democracy, improving the life chances of the residents of Bagdhad or educating Afghan girls - nation building in short - was never popular. The news of Bin Laden's death will, I predict, encourage many Americans to believe that the war which began on 11th September 2001 is finally over and that it is time their boys came home.
A President who some said could not be re-elected may soon look hard to beat. His political advisers are likely to want to seal this victory by ending operations in Afghanistan as soon as they can. It is Obama, just as much David Cameron, who will determine when British troops come home.
Obama has looked mightily reluctant to get drawn further into conflict in Libya or into new conflicts elsewhere. There is a danger for David Cameron that today's news increases that reluctance. 'After a popular victory why risk a defeat.' his advisers may ask.
The security challenges of 2011 - in Syria, Libya, Egypt Iran and elsewhere - have little to do with the man George Bush identified as his country's greatest enemy in 2001. Nevertheless, today's news of the death of Osama Bin Laden could have a profound effect on the decisions taken about the future.