Isis already has a new leader in place after the death of its former figurehead, Abu Bakr al-Baghdadi, it has been reported.
Baghdadi blew himself up after a US military operation in Syria, President Donald Trump announced on Sunday.
He said Baghdadi ran into a dead-end tunnel and ignited an explosive vest, killing himself and three of his young children after being surrounded by specialist forces.
Mr Trump said Baghdadi died as "a coward, running and crying". The US president also threatened to drop Isis jihadis “right at the UK border”.
But Newsweek has reported that Baghdadi’s successor as Isis leader is already in place.
Abdullah Qardash, known as “The Professor”, was picked by Baghdadi to run the terror group’s “Muslim affairs” in August, but it is thought he replaced his ailing predecessor.
An intelligence official told Newsweek: "Baghdadi was a figurehead. He was not involved in operations or day-to-day.
"All Baghdadi did was say yes or no - no planning."
Qardash, sometimes spelled “Kardesh” and also known as Hajji Abdullah al-Afari, is a former Iraqi military officer who served under Saddam Hussein.
After the US invasion of Iraq in 2003, he ended up in prison, meeting Baghdadi at the Camp Bucca detention centre in Basra.
After his release, Qardash reportedly served as a member of al-Qaeda, before later joining Isis.
Qardash is known as the group’s chief legislator and policymaker, and took over day-to-day running of the group in August. However, after the group’s recent defeats, it is split into separate cells.
In March, Isis was forced by American troops and Kurdish forces out of the last portion of its self-declared "caliphate", which once spanned a swathe of Iraq and Syria.
But security experts say the militant group, which rose from the remnants of al-Qaeda in Iraq after that group's defeat by US-led forces in 2008, remains a dangerous threat in Iraq, Afghanistan and beyond.
Chris Costa, a former senior director for counter-terrorism for the National Security Council in the Trump administration, said: "The bottom line is: this puts the enemy on its heels, but the ideology - and this sounds so cliched - is not dead."
US forces, perhaps in reduced numbers, will continue hunting and attacking key Isis targets, even as Mr Trump says he is committed to a 2016 campaign pledge to bring them home and end "endless wars" started under his predecessors.
Mr Trump earlier this month went from declaring a near-complete withdrawal of US forces from Syria to deciding that some - perhaps several hundred - must stay to keep eastern Syria's oil fields from falling back into the hands of Isis.
Mr Trump also agreed to keep about 150 US troops at a base in southern Syria.
According to defence officials in Iraq and Afghanistan who study Isis and have watched its movements, the group is growing in power and numbers outside of Syria.
Its flagship affiliate is known as Isis-Khorasan in Afghanistan, and it is expanding into other countries, including Pakistan, Tajikistan, Iran, India, Bangladesh and Indonesia.
British Defence Secretary Ben Wallace said he welcomed the US action against what was arguably the world's most wanted man.
"Isis is one of the most murderous terrorist organisations of our generation," he said.
"Their leaders have twisted Islam to groom thousands of people into joining their evil cause. I welcome the action that has been taken.
"The world will not miss al-Baghdadi."