According to media reports, Anwar al-Awlaki, the Yemeni-American Islamist radical who played an increasingly influential role in the al-Qaeda network, was killed in a CIA drone strike earlier today in Yemen. Awlaki was reported to have been killed at least twice before, and one of his brothers reportedly already has denied today’s report of his death, but U.S. government officials and Yemeni officials appear to be certain of his death this time.

Anwar al-Awlaki, a U.S.-born cleric linked to al Qaeda’s Yemen-based wing

An ultra-radical Islamist ideologue, Awlaki had played an important role in promulgating al-Qaeda’s violent ideology, recruiting young Muslims, particularly in the West, and inciting them to engage in terrorist attacks. Born in the U.S., the charismatic Awlaki was one of few al-Qaeda leaders who had a proven record of inciting terrorism by American Muslims.

Awlaki was linked to several terrorist attacks in the U.S., including the 2009 shootings at Ft. Hood by Major Nidal Hasan that killed 13 people; the botched 2009 Christmas Day attack by the “underwear bomber”; and the failed attempt to detonate a car bomb in New York’s Times Square in May 2010.

Awlaki also was known to be close associate of at least two of the 9/11 hijackers and served as their “spiritual guide” while he served as a preacher at mosques in San Diego and Falls Church, Virginia.

Awlaki left the United States in 2002 and spent two years preaching jihad in Great Britain before moving to Yemen in 2004. Yemen, the ancestral homeland of Osama bin Laden, long has been an important staging area for al-Qaeda terrorist attacks. While in Yemen, he was protected by his father’s kinsmen, the powerful Awlaki tribe.

After he fled to Yemen, Awlaki declared open war on the United States. He served as part of al-Qaeda in the Arabian Peninsula’s (AQAP) “Foreign Operations Unit” and appears to have played an increasingly operational role in AQAP’s terrorist operations.

Awlaki reportedly was killed while riding in a convoy in Yemen. Killed along with him was Samir Khan, a Pakistani-American who reportedly edited the al-Qaeda online propaganda newsletter, Inspire.

Terrorism experts believe that Awlaki will be difficult to replace due to his high-profile role as an ideological publicist and recruiter, particularly for English-speaking Muslims open to al-Qaeda’s violent ideology.

But the United States must remain vigilantly engaged in combating terrorism in Yemen, which has been destabilized by an intensifying civil war, as well as winning the long war against al-Qaeda.