But they say the successful attack also demonstrates that the US remains a powerful military force with the ability to strike from distance, restoring some of the credibility it lost after the withdrawal from Afghanistan last year.
It will also enhance President Joe Biden’s reputation on foreign policy in the wake of his decision to withdraw all US troops from the country in August last year, said former Brigadier Ben Barry of the International Institute for Strategic Studies.
“This is good news for Biden in that he was criticised for the chaotic withdrawal but striking at terrorists over the horizon has vindicated that decision,” he said. “It is a reminder to terrorists everywhere that the US has formidable capabilities.”
A person or a network in Afghanistan who wanted Al Zawahiri removed may even have tipped off the Americans, with the Taliban, ISIS and even younger Al Qaeda operatives all having potential motivation.
It is possible that the group could now go for a “young and hip” new leader who knows more about the West and the role of social media, counter-terrorist analyst Dr Michele Groppi told The National.
He argued that the younger wing of Al Qaeda, who are connected to the Haqqani network which appears to have been sheltering Al Zawahiri, might have turned in their leader for a more energised approach. There was also a $25 million US bounty on his head.
“The younger Al Qaeda speak English and understand the power of social media, especially its ability to attract new recruits, which they saw ISIS achieve via various platforms in Syria,” Dr Groppi said.
Al Zawahiri had taken to making more video recordings which were regarded as old-fashioned and less energising than the more modern propaganda clips used by ISIS and others.
But the possibility that the Taliban ordered his removal “makes some sense”, said the lecturer on defence studies from King's College London. “They understand that they cannot function without money, bankers, lawyers and most importantly international recognition.”
It is believed that US intelligence knew that Al Zawahiri’s nephew had arrived a few days earlier and it was “impossible that the Taliban did not know”.
Equally, the ISIS Afghan offshoot known as ISIS-K could have informed on Al Zawahiri “to cause havoc in their Al Qaeda ranks and to embarrass them”.
“My sources really doubt that the US carried out this attack based on their own intelligence — someone knew and someone talked,” Dr Groppi said.
Brig Barry said the killing of a leading ally in their capital city had “blown a hole in the Taliban’s credibility”, demonstrating that Afghanistan was not “safe for international terrorism”.
But he agreed it could be a move by the Taliban to “reduce the threat” of Al Qaeda, while potentially developing a relationship with the US.
Without international recognition and financial support, the country could soon sink back into a civil war that would produce more deadly terrorism, Brig Barry said.
The lethal strike was also a message to Russia that the US military has the resources to hit a target at great distance in a country where it does not have presence on the ground, said former British military commander Col Hamish de Breton-Gordon.
“This was an impressive demonstration by the US that it can carry out a precision strike in faraway places, taking out some who is totally evil," he said.
“The US and Nato are 21st century militaries, so there will be a few Russian generals in Ukraine who will be looking skywards with considerable more anxiety today. This will embolden the Ukrainians and terrify the Russians.
“It will also make the Taliban think twice that despite having no troops in Afghanistan, the US can still conduct forensic strikes.”
Col de Breton-Gordon said it would also show other terrorist groups operating in Afghanistan, such as ISIS, that it cannot “operate unhindered”.
Al Qaeda damaged but not destroyed
Given the threat to Al Zawahiri’s life since he took over from Osama bin Laden in 2011, Al Qaeda are likely to have a successor ready, so the killing will be “serious blow” to the organisation “but not a mortal one”, said Dr Groppi.
“They have an incredible ability to adapt and reform,” he said.
The terrorists are now expected to regroup in the ungoverned territory on the Afghanistan-Pakistan border.
“Al Qaeda will remain a threat but not in the short term, for now they will be much more focused on survival,” Dr Groppi said. “They need to re-establish their chain of command and their structure, which was pretty hierarchical under Al Zawahiri and in the longer term they will pose an everlasting threat to the West.”
But one security source with contacts in Afghanistan argued that Al Zawahiri had been “elderly” and had “no direct operational role” in Al Qaeda activities.
“He was allowed to live in Kabul because the Taliban have a strong sense of hospitality but I don’t think they will complain that much now that he’s dead,” the source said. “Sources in Kabul are reporting that there’s no unrest. This was a bit of tidying and bit of closure for Joe Biden.
“The Taliban also know that if they become host to international terrorism again, they will experience the same deadly operations that they did after 9/11.”