Anwar Al-Awlaki, and a second American, Samir Khan, were killed by a joint CIA-US air strike on their convoy in Yemen early Friday. Both men played major roles in inspiring attacks against the US, and their killings are a devastating double blow to Al-Qaeda’s most dangerous franchise.

Seeking to justify the targeted killing of a US citizen, Obama outlined Al-Awlaki’s involvement in planning and directing the murders of other Americans.

“He directed the failed attempt to blow up an airplane on Christmas Day in 2009. He directed the failed attempt to blow up US cargo planes in 2010,” Obama said. “And he repeatedly called on individuals in the United States and around the globe to kill innocent men, women and children to advance a murderous agenda.”

After three weeks of tracking the targets, US armed drones and fighter jets shadowed Al-Alwaki’s convoy before armed drones launched their lethal strike early Friday. The strike killed four operatives in all, officials said. All US officials spoke on condition of anonymity to discuss matters of intelligence.

Al-Awlai was targeted in the killing, but Khan, who edited the slick Jihadi Internet magazine, apparently was not targeted directly.

Al-Awlaki played a “significant operational role” in plotting and inspiring attacks on the United States, US officials said Friday. Khan, who was from North Carolina, was not considered operational but had published seven issues of Inspire Magazine, offering advice on how to make bombs and the use of weapons. The magazine was widely read.