How the CIA tracked the leader of Al Qaeda

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.

Analysts search for that kind of pattern-of-life intelligence, any habit the C.I.A. can exploit. In al-Zawahri’s case, his long balcony visits gave the agency an opportunity for a clear missile shot that could avoid collateral damage…

U.S. officials quickly decided to target him, but the location of the house posed problems. It was in the Sherpur neighborhood of Kabul, an urban area of closely spaced houses. A missile armed with a large explosive could damage nearby homes. And any sort of incursion by Special Operations forces would be prohibitively dangerous, limiting the options for the U.S. government to conduct a strike.

The search for al-Zawahri carried huge importance for the agency. After the U.S. invasion of Afghanistan, the C.I.A. base in Khost Province became home to a targeting group dedicated to tracking both Bin Laden and al-Zawahri. It was one of the leads developed by the C.I.A. to track al-Zawahri that proved disastrous for the agency’s officers at that base, Camp Chapman.