US President Joe Biden said 'justice has been delivered' after confirming in a White House speech that a US drone strike killed al-Qaeda leader Ayman al-Zawahiri. Video / AP
It was a well-worn routine, and one that ultimately led to his death.
Shortly after dawn on Sunday, Ayman al-Zawahiri, the al-Qaeda leader, was taking in the air on the third-floor balcony of his safe house in the upmarket Kabul neighbourhood of Sherpur, a short walk from the British Embassy,having completed his morning prayer.
As the sun rose over the capital, he would have been blissfully unaware of the CIA Reaper drone circling tens of thousands of feet overhead.
At 6.18am, the unmanned aircraft fired two R9X "ninja" Hellfires, a new-age hyper-accurate missile system which replaces explosives with six razor-like blades.
Moments later Zawahiri was dead, shredded, his jihad over. His family, just feet away inside the building, were unharmed.
Announcing the mission's success in a live TV address on Monday, President Joe Biden was blunt.
"Justice has been delivered," he said. "This terrorist leader is no more."
The strike against Osama bin Laden's former deputy, and one of the final masterminds of 9/11 still at large, brought to an end a manhunt that spanned a generation.
For more than a decade the trail had gone cold. Zawahiri appeared in a video last year on the anniversary of the 2001 attacks but it offered scarce clues as to his whereabouts.
Earlier this year, however, US intelligence heard whispers that the Egyptian former doctor who had succeeded bin Laden as head of al-Qaeda in 2011 was back in Afghanistan.
In early April, top security officials were made aware that Zawahiri's wife, their daughter and grandchildren had moved into a safe house in the old diplomatic quarter and were using textbook terrorist tradecraft in an effort not to be followed.
They then briefed the president. Was it possible that, despite the Doha agreement with Donald Trump's administration, the re-established Taliban regime was again harbouring terrorists?
American spies soon became increasingly confident that Zawahiri was indeed living at the house. As in the case of bin Laden 11 years earlier, they began weaving together different threads of intelligence to build up a so-called "pattern of life" to confirm his presence.
In all those weeks, US intelligence were never once aware of the person they believed to be the al-Qaeda boss leaving the building. However, he was observed to spend substantial amounts of time on the balcony.
The echoes of Abbottabad, the sleepy Pakistani compound where bin Laden hid from surveillance but was finally killed by the Navy Seals in 2011, were marked. John Kirby, from the National Security Council, told CNN yesterday that US spies had spent "weeks, if not several months, of making sure that we had the right guy".
"Once we knew that we had an effective pattern of life and opportunities that could be taken, it was really down to stitching together how you were going to take that opportunity and with what."
The president received updates throughout May and June. By the start of July, intelligence chiefs had come up with a plan.
At a briefing in the White House situation room on July 1, William Burns, the CIA director, and others showed Biden a detailed model of the house Zawahiri was staying in.
The president is said to have asked questions about the weather, the sturdiness of the building materials and other factors that might affect the success of a missile strike and the likelihood of civilian casualties. On July 25, Biden convened his advisers and key cabinet members for a final meeting on the latest intelligence. Not for the first time, he asked about options other than air strike.
Ayman al-Zawahiri was killed in his home. Photo / Supplied by AP
When these were "systematically eliminated", the president gave the green light for a tailored missile strike on the condition that it minimise, as far as possible, civilian casualties.
The choice of missile may well have been crucial in authorising arguably the most significant strike since 2011. Made by Lockheed Martin and Northrop Grumman, the R9X Hellfire marks a new generation of precision weapon using six blades of reinforced metal that extend moments before hitting the target.
By abandoning the explosive warhead, US military and spy chiefs hope to leave behind the routine collateral damage - the seemingly relentless killing of innocent family members, neighbours and bystanders - that became such a hallmark of the war on terror. It was used in January 2019 to take out Taliban leader Mohibullah, as well as the USS Cole bombing suspect Jamel Ahmed Mohammed Ali al-Badawi in Yemen.
In deciding whether and how best to attack Zawahiri, the White House will have been mindful of the "horrible mistake" made last year when 10 innocent people were killed in a missile strike when they were mistaken for members of Islamic State following the US withdrawal from Afghanistan.
As Kirby put it: "The president made it very clear when he made the decision that he wanted to make sure we avoided civilian casualties, and we know we did from a series of intelligence and other sources that we have available to us."
