Anwar al-Awlaki in Yemen, 2008. (Muhammad ud-Deen/Creative Commons)

CNN reported that the worldwide alert in effect until Nov. 30 urges those traveling abroad to register with the U.S. government for emergency contact.

The FBI and Department of Homeland Security issued a joint bulletin late Friday that said the deaths of al-Awlaki, Samir Khan and two others "could provide motivation for homeland attacks" by "homegrown violent extremists."

The New York Times reported yesterday that the assassination of one of Al Qaeda's top propagandist and strategist is the result of a two-year-long manhunt that sustained "a wrenching legal debate in Washington about he legality — and morality — of putting an American citizen on a list of top militants marked for death."

Al-Awlaki was born in New Mexico, but moved to Yemen with his family at the age of 7. He attended college in the U.S. in 1991 and stayed until 2002. According to the CNN report, he "interacted with three of the men who went on to become September 11, 2001, hijackers," but later condemned the attack. He has also been named in connection with the underwear bomber who attempted to take down a flight landing in Detroit in December 2009, as well as the Fort Hood shooter, Maj. Nidal Hasan.

President Obama said the assassination was "a major blow to Al Quaeda's most active operational affiliate." Reports of Saturday's warning note that a similar alert was issued following the killing of Osama bin Laden in May of this year.

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