The killing on Saturday of al Qaeda leader Ayman al Zawahiri serves the causes of justice and global security. It is a tactical counterterrorism victory that accrues strategic benefit via a weakened al Qaeda.

Still, that Zawahiri was killed after months of residence in the Afghan capital of Kabul evinces a broader strategic loss in terms of U.S. security. It proves the increasing confidence of the Taliban and al Qaeda in reconstituting their traditional, formal relationship as ideological and practical allies.

At first glance, the July 31 killing of al-Qaeda chief Ayman al-Zawahiri by a US drone attack in Kabul, Afghanistan, appears to be the most significant setback the group has experienced since the death of its founder, Osama bin Laden, in 2011.

Ayman al-Zawahiri was an intellectual driving force of al-Qaeda, and Osama bin Laden’s successor as the Islamist group’s leader since 2011. His death in a US strike in Kabul brings justice of sorts for the families of victims of a string of terrorist atrocities including the 9/11 attacks on the US. It demonstrates America’s ability to continue to mount “over-the-horizon” counter-terrorism operations, nearly a year after the ignominious US withdrawal from Afghanistan.