He had been hunted for more than a decade, and the organisation he had built was designed partly on the assumption this day would come

The violent death of Abu Bakr al-Baghdadi, leader of the Islamic State, in a raid by U.S. forces announced Sunday by President Donald Trump, is a significant blow to the world’s most fearsome terrorist group.

The violent death of Abu Bakr al-Baghdadi, leader of the Islamic State, in a raid by U.S. forces announced Sunday by President Donald Trump, is a significant blow to the world’s most fearsome terrorist group. But analysts said it was unlikely to freeze attempts by Islamic State franchises and sympathisers around the world to sow mayhem and fear in the name of their extremist ideology.

Under al-Baghdadi, the Islamic State largely ran on its own. While he demanded fealty and built a cult of personality around himself — followers considered him the leader of Muslims worldwide — he was obsessed with security and is known to have given subordinates considerable latitude to act autonomously. Numerous references in Islamic State propaganda offer reminders that its leaders may come and go, but the movement remains.

After all, the founder of the Islamic State and two successors were killed before al-Baghdadi became its leader and vastly expanded the group’s sway in the Middle East and beyond.

And in his final years, al-Baghdadi stuck to such strict safety measures that he was believed to have been surrounded by a small circle of direct contacts, including wives and children and a few trusted associates. He limited communications with the outside world, according to U.S. and Iraqi intelligence officials, which meant his organisation operated with sparing input from him, lessening the practical effects of his demise.

“For sure it is important, but we know from what we have seen from other organisations that getting rid of the leader does not get rid of the organisation,” said Hassan Abu Hanieh, a Jordanian expert on extremist groups. “ISIS has created a new structure that is less centralised, and it will continue, even without al-Baghdadi.”

Just in the past year, the group has claimed responsibility for deadly attacks in Afghanistan including a mosque bombing that killed more than 70 people; a wedding blast that killed 63; a shooting at a Christmas market in Strasbourg, France, that killed five people; a Cathedral bombing by an Islamic State affiliate in the Philippines that killed 22 people; a string of bombings in Sri Lanka that killed more than 250 people; and other attacks in Russia, Egypt, Australia and elsewhere.

Omar Abu Layla, a Syrian who heads an activist news network called Deir Ezzour 24, said he expected al-Baghdadi’s death would demoralise some followers while enraging others who would seek to avenge him.

“Some of the cells in Europe and the West could try to carry out attacks to show that ‘Even without al-Baghdadi, we will continue,’” he said.

Trump’s triumphal announcement that al-Baghdadi “died like a dog” in northern Syria’s Idlib province came as the Islamic State had shown signs of reconstituting in remnants of its self-proclaimed caliphate, which once spanned a swath of Syria and Iraq before it was destroyed by U.S.-led forces in March.

But even as the military campaign chipped away at the Islamic State’s caliphate, the group was branching out, founding and supporting new franchises and cultivating relationships in Afghanistan, Libya, the Philippines, the Sinai Peninsula in Egypt, Nigeria and elsewhere.

While the branches followed its ideology, they largely operated independently, plotting attacks on local security forces, seizing control of territory or parts of cities and battling other extremist groups for resources. Most were seen primarily as threats to their own countries or their neighbours, but U.S. officials worried that some franchises, like those in Afghanistan or Libya, could oversee attacks in the West.

Although the Islamic State may now be a shadow of its former self, a recent report by an inspector general for the U.S.-led operation against it estimated that the organisation still has between 14,000 and 18,000 members in Iraq and Syria, including up to 3,000 foreigners. But the report noted that estimates varied widely and that the group maintained an extensive worldwide social media effort to recruit new fighters.

As the Islamic State moved away from a centralised command structure to a more diffuse model, it also intensified calls on operatives acting alone or in small groups to plan and execute their own attacks, which were then amplified by the organisation's media network.

Under this strategy, anyone, anywhere could act in the group’s name. That multiplied the Islamic State’s lethality by remotely inspiring attacks, carried out by disciples who had never set foot in a training camp. They were responsible for deadly assaults ranging from a shooting at an office party in San Bernardino, California, to a rampage by a van driver in Barcelona, Spain.

While little is known about how al-Baghdadi spent his last months, he appeared in a video released in April, sitting cross-legged on a cushion with an assault rifle by his side and praising the Sri Lanka church bombers.