Like Osama bin Laden before him, Baghdadi had been hiding in a secure compound, although this time not in Pakistan, but in northern Syria's Idlib province near the town of Barisha, not far from the Turkish border.

Trump's thunder was stolen to some extent by US military personnel, who presumably don't have much time for him, leaking details of the Joint Special Operations Command (JSOC) Delta Force operation before Trump was able to make his announcement.

The operation was named Operation Kayla Mueller to honour an American humanitarian worker abducted by Islamic State in August 2013 at Aleppo in Syria, soon after she left a Doctors Without Borders hospital. In August 2015, The New York Times reported that Mueller had been forced into marriage to Baghdadi, who raped her repeatedly. She had also been tortured. US special forces planned or attempted to rescue her and other American captives on several occasions, but without success. Islamic State announced in February 2015 that she had been killed by a Jordanian air strike.

It is not clear whether Baghdadi was injured during the same air strike, but he was believed to be ill or injured from shrapnel wounds, and in poor health. The last time he was seen on video was in April 2019, when he was shown seated with a group of people, praising the Sri Lanka bombers who had just killed 259 people.

The JSOC operation against Baghdadi would presumably have been cleared beforehand with Turkey and Russia as it involved eight American helicopters traversing areas controlled by their forces since the American withdrawal from northern Syria.

In a move that perhaps anticipated his death, Baghdadi announced on August 7 through the Islamic State-affiliated media organisation AMAQ that his successor would be his close associate Abdullah Qardash. Like Baghdadi, Qardash had been an officer in the old Iraqi army and had been detained by the Americans at Camp Bucca in Iraq in 2004, and later released.

Baghdadi and Qardash were embittered against the Americans who had promised them a future in a new Iraqi Army if they surrendered following the coalition invasion of Iraq. The promise was not kept, leading them to shift their allegiances to al-Qaeda. This transition was made easier because they were detained at Camp Bucca along with extremists like Abu Musab al-Zarqawi, who became the first "emir" of al-Qaeda in Iraq.

On May 16, 2010, Baghdadi was announced as leader of al-Qaeda in Iraq, following the death of his predecessor. Under Baghdadi, the group expanded into Syria and tried to take over the al-Qaeda affiliate there, known as Jabhat al-Nusra. This move was resisted by al-Qaeda emir Ayman al-Zawahiri, who told Baghdadi to confine his activities to Iraq.

On April 8, 2013, Baghdadi announced the formation of the Islamic State of Iraq and the Levant (ISIL) which absorbed some 80 percent of the members of Jabhat al-Nusra. This led to bitter fighting between the two main Sunni extremist elements in Syria, causing hundreds of deaths and making any future reconciliation between Baghdadi and al-Qaeda leader Dr Zawahiri unlikely.

On June 29, 2014, ISIL announced the establishment of a global caliphate with al-Baghdadi as its caliph, to be known as "Caliph Ibrahim". ISIL was renamed the Islamic State, or IS. Probably the high point of Islamic State in Syria and Iraq was when Baghdadi mounted the pulpit in Mosul's Grand al-Nuri Mosque in July 2014, after the fall of Mosul, to deliver his first speech as "Caliph Ibrahim".

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Since then, of course, Islamic State has lost most of its territorial gains in Iraq and Syria, and now only has pockets of resistance there, but with some promising expansion prospects in Iraq due to rural Sunni disenchantment with the Shiite-dominated government in Baghdad.

This year Islamic State has emphasised the importance of global operations and highlighted its progress in Libya, Somalia, Afghanistan and the Philippines. At the same time, it has continued to encourage followers in the West to conduct low-tech, high-impact attacks - using vehicles and knives as weapons - that are difficult for Western intelligence agencies to detect and counter because they require only minimal preparation.

Looking forward, there is now potential for Islamic State and al-Qaeda to work together or combine activities under Abdullah Qardash. The likely successor to lead al-Qaeda had been Osama bin Laden's son Hamza bin Laden, but he was reported by the US to have been killed in an air strike - probably in the Afghanistan-Pakistan border area, earlier this year. However, his death has not been confirmed by al-Qaeda.

Qardash does not have to maintain Baghdadi's rage against Dr Zawahiri at a time when al-Qaeda is facing generational change, with Zawahiri likely to retire in the next few years. Both groups have parallel aims to promote Sunni Islam globally through violence.

Islamic State is down but not out - and the claim by Trump that it is finished as a security problem is characteristically at variance with the facts. Apparently 11 of Baghdadi's children survived the JSOC raid, and they too could - like Hamza bin Laden - become a problem for the future.