Zawahiri read alone on balcony, a pattern-of-life intelligence CIA used to kill him

Zawahiri, who played a key role in the 9/11 attacks and later formed Al-Qaeda's regional affiliate in the Indian subcontinent, was killed in a US drone strike

Al-Qaeda leader Ayman al-Zawahiri liked to read alone on the balcony of his Kabul safe house early in the morning, a "pattern-of-life intelligence" that eventually gave American intelligence agencies the chance to carry out a precision strike that killed one of the world's most wanted terrorists, a report said.

Zawahiri, who played a key role in the 9/11 attacks and later formed Al-Qaeda's regional affiliate in the Indian subcontinent, was killed in a US drone strike on Saturday evening.

"Intelligence officers made a crucial discovery this spring after tracking Ayman al-Zawahri, the leader of Al Qaeda, to Kabul, Afghanistan: He liked to read alone on the balcony of his safe house early in the morning," The New York Times (NYT) said in a report titled 'How the CIA Tracked the Leader of Al Qaeda'.

The report said that analysts search for "pattern-of-life intelligence", which means any habit the CIA can exploit to hunt down and target terrorists. "In al-Zawahri's case, his long balcony visits gave the agency an opportunity for a clear missile shot that could avoid collateral damage," it said.

Once intelligence agencies confirmed the location of Zawahiri's safe house, "the CIA followed the playbook it wrote during the hunt for (Osama) Bin Laden. The agency built a model of the site and sought to learn everything about it."

"Analysts eventually identified a figure who lingered on the balcony reading, but never left the house, as al-Zawahiri," the NYT report said.

On July 25, Biden authorised the CIA to conduct the airstrike "when the opportunity presented itself".