The killing of al-Qaeda chief Ayman al-Zawahiri in a US drone strike on his hideout in Afghanistan's capital, Kabul, opens the way for a potentially troubled succession process for the extremist group, experts said.
The Egyptian extremist, killed Sunday (July 31) in a high-precision strike on his "safe house" in Sherpur, one of Kabul's most affluent neighbourhoods, never attempted to replicate the charisma and influence of his predecessor.
But after US special forces killed Osama bin Laden in Pakistan in 2011, he played a key role in encouraging a decentralisation of the group, which resulted in al-Qaeda franchises emerging all over the globe.
These include al-Shabaab, which still controls a large chunk of rural Somalia, the JNIM active in West Africa -- in particular Mali -- and the al-Qaeda in the Indian Subcontinent (AQIS) branch.
Al-Zawahiri "accepted major new players in the al-Qaeda network", said Hans-Jakob Schindler, director of the NGO Counter-Extremism Project and a former UN advisor.
"So it is a blow to al-Qaeda," he said.
Potential Egyptian successor
Among the likeliest successors are two other Egyptians: Saif al-Adel and Abu Abd al-Karim al-Masri.
Al-Adel is a former Egyptian special forces officer and figure in the old guard of al-Qaeda, whose presence has been reported in Iran.
After joining the Egyptian extremist movement in the 1980s, he was arrested and then released, ending up in Afghanistan, which was the base for bin Laden and al-Zawahiri, and joining al-Qaeda.
According to the Counter Extremism Project (CEP), he was arrested in Iran in 2003 and freed in 2015 in a prisoner exchange. He was still suspected of being in Iran in 2018 as one of al-Zawahiri's key deputies.
"Al-Adel played a crucial role in building al-Qaeda's operational capabilities and quickly ascended the hierarchy," the CEP said.
Barak Mendelsohn, a political scientist at Haverford College in the United States and author of several books on al-Qaeda, has described al-Adel as a "big name" in the movement who "should be the next in line".
But he stressed that al-Adel had spent several years hiding in Iran, thus possibly staying away from al-Qaeda's new generation of leaders.
"I am not sure how strong his position is within al-Qaeda, especially now that the old generation, basically all the old guard, is dead," he said.
Iran's Shia rulers officially oppose al-Qaeda, but the Islamic Republic has been repeatedly accused of co-operating with the network and giving sanctuary to its leaders.
Al-Masri, the other Egyptian contender to succeed al-Zawahiri, also known as "Karim", is part of the leadership of Syrian extremist group Hurras al-Deen and might be in Syria.
A Yemeni leader of Hurras al-Deen was killed June 27 in a US drone strike on the edge of Idlib city in northwestern Syria as he travelled alone on a motorbike, and two other officials of the group were killed in similar style last September.
The US State Department's Rewards for Justice programme is offering a reward of up to $5 million for information on al-Masri, described as a "veteran member of al-Qaeda and senior leader of Hurras al-Deen".
"In 2018, al-Masri was a member of Hurras al-Deen's shura council, the group’s senior decision-making body," according to the Rewards for Justice website.
He "served as a mediator between Hurras al-Deen and Tahrir al-Sham, an al-Qaeda-linked umbrella group from which Hurras al-Deen had broken away," it said.
Succession is 'the big question'
"Al-Zawahiri was not involved in the day-to-day decision-making of the affiliates," Schindler said.
"But you need a figurehead with a certain prominence and seniority because all the heads of all the affiliates need to swear personal loyalty to him," he added.
"So replacing him is going to be a bit of a challenge."
The al-Qaeda succession is the "big question" in the wake of the killing of al-Zawahiri, said SITE Intelligence Group director and co-founder Rita Katz.
"Unlike the situation after Osama bin Laden's killing, so much of its leadership has moved to Syria, where many were killed," she said.
She said that little is known about the whereabouts of al-Adel but emphasised it was far from certain he was still in Iran, where observers say he spent some two decades.
"Rumours are that he was released from prison in Iran and moved to Syria. However, not much is known," she said.
The killing of a number of al-Qaeda old guard figures in recent years has left the network with a "dwindling bench of potential successors", said the Soufan Centre, a US-based security research organisation, in an intelligence update Tuesday.
Al-Adel's "long presence" in overwhelmingly Shia Iran "might taint his candidature in certain circles", it said.
Younger al-Qaeda cadres may prefer a figure like al-Masri, who in Syria "worked assiduously to cultivate ties with potential recruits more focused on local targets and motivated by parochial grievances in regions engulfed by civil war and insurgency".
"The selection of al-Qaeda's next leader will tell a great deal about the future plans of the organisation," it said.