There is something strange about an assassination without a corpse. As with Eva Peron, the First Lady of Argentina whose body mysteriously vanished for 16 years, the absence of a cadaver is unsettling. Save for Barack Obama’s word, there is little concrete evidence that Osama bin Laden is actually dead. Before long, the US president will be obliged to produce the photos – inflammatory or not – of the slain al-Qaeda leader.

Of course, few can seriously doubt that bin Laden has been killed, nor that the world is better for it. Few can deny either the psychological boost to America of bringing its most hated adversary to bloody account. But the danger is that the outcomes of the deed will prove as hollow as an assassination without a corpse. Mr Obama’s victory may turn out to be Pyrrhic.

This is partly because the world has moved on since the time when bin Laden was judged the world’s most dangerous man. By all accounts, for the past five years he has been holed up in the leafy environs of Abbottabad, without phone or e-mail. Rather than an organiser of terror, he has become an idea of terror. His cancerous thought has metastasised throughout Pakistan, to Yemen, Somalia and elsewhere. An idea, naturally, is harder to kill than a person.