The world yesterday woke up to the news that Osama bin Laden, the head of the al-Qaeda terrorist group, was dead, killed in a US raid in a compound in Pakistan.

A hero for fundamentalist Muslims – Hamas have described the killing as the “assassination of an Arab holy warrior – a much-hated terrorist for the West – British PM David Cameron called his activities “poisonous extremism” – bin Laden was the mastermind behind the attacks of 11 September 2001 against America. More than 3,000 people were killed in the attack on the Twin Towers in New York, and the physical and emotional scars are still there.

It took the US 10 years to find him and plan his death, and it was only when the mission was accomplished that US President Barack Obama announced it to the world, saying that it was a “good and historic day”.

People in the US – but not only there – have celebrated his death. They have taken to the streets to express their satisfaction that the leader of the terrorist group that changed the course of history and, most of all, affected their day-to-day lives, was finally gone.

His death brings to an end his reign of terror, but the battle against terrorism is far from being over. Yesterday, immediately after his death was announced, alerts were issued against possible reprisals from his followers. Bin Laden was the top leader, but his al-Qaeda group had and has terrorist cells all around the world, and they will not take his killing lying down. There are and will be others who want to take over from bin Laden.

This is why his death could bring about a beginning – the possibility that his killing will be avenged is great. Maybe not today, maybe not tomorrow, but there will come a time when his followers will retaliate. Bin Laden was the most wanted man, but he was not operating on his own. And his death could spark a surge in fundamentalism.

Bin Laden’s death is a psychological reprieve, especially for the relatives of the victims of the 9/11 attacks. It is also a big boost for Obama, who finished off what George W. Bush started but could not complete.

But the impact on al-Qaeda remains to be seen. And Obama knows what he is dealing with. “His death does not mark the end of our effort. There’s no doubt that al-Qaeda will continue to pursue attacks against us. We must and we will remain vigilant,” he said in his statement to the media.