The CIA drone strike that killed Al Qaeda leader Anwar al-Awlaki and chief propagandist Samir Khan may also have taken out the terror organization's top bombmaker.
Reports say that Ibrahim al-Asiri, who is believed to have constructed both the "underwear" bomb used in the attempted bombing of Northwest flight 253 and the bombs in last year's parcel bomb plot, may have been with Awlaki and Khan when missiles from a U.S. drone struck their vehicle in Yemen Friday.
However, there has been no confirmation yet of al-Asiri's death from officials.
Asiri's fingerprint was found on the bomb allegedly packed into the underwear of Umar Abdulmutallab, accused of trying to bring Northwest 253 on Christmas 2009 over Detroit.
The chief target, radical American-born cleric Awlaki, was a major al Qaeda figure who U.S. officials say inspired numerous terror plots against the U.S.
The Department of Homeland Security and the FBI issued a joint bulletin warning of the potential for retribution by jihadis.
"We assess US and Western-based sympathizers may attempt to exploit [Awlaki's] death due to his popularity as a violent extremist whose speeches and writings are widely available on the Internet. While there is currently no information suggesting retaliatory US-based activities in response to [Awlaki's] death, we are concerned about the possibility that autonomous extremists may react violently.
A senior U.S. official told ABC News the U.S. had been tracking the high-profile jihadist for some time and had just been waiting for the perfect moment to strike.
A Yemeni official said al-Awlaki was killed along with an unknown number of al Qaeda confederates.
"They were waiting for the right opportunity to get him away from any civilians," a senior administration official told ABC News.
President Obama said in an announcement Friday that al-Awlaki's death was a "major blow" to al Qaeda's most operational affiliate, the Yemen-based al Qaeda in the Arabian Peninsula (AQAP), and that the successful operation against him was a tribute to the intelligence community and to Yemen.
Born in New Mexico and educated in Colorado, al-Awlaki rose to prominence among extremists as a member AQAP and was a vocal preacher of jihad. His online teachings have been cited as part of the motivation behind several attacks on the U.S. homeland -- from the Fort Hood Massacre to the attempted Christmas Day bombing and the Times Square bomb plot.
In 2010, al-Awlaki was declared a "specially designated global terrorist" and became the first U.S. citizen ever to be placed on a White House-approved list for targeted killing.
He nearly met his fate shortly after U.S. Navy SEALs killed al Qaeda founder Osama bin Laden in early May when a drone strike hit the convoy he was traveling but barely missed him.
Earlier this year, America's chief counter-terrorism official Michael Leiter called him and AQAP "probably the most significant risk to the U.S. homeland."
The most recent issue of an English-language al Qaeda magazine called "Inspire" prominently featured an advertisement for an upcoming message from al-Awlaki titled "Targeting the Populations of Countries That Are at War With the Muslims."
The advertisement used as its background an image of Grand Central Station with U.S. security officials said in a law enforcement bulletin could have been "an allusion to the continued interest of extremists in general of targeting New York City for terrorist attacks."
Secretary of Defense Leon Panetta told reporters the U.S. was safer now that al-Awlaki had been killed.
"We had always had a tremendous concern that after getting bin Laden, someone like al-Awlaki was a primary target because of his continuing efforts to plan attacks against the United States," he said. "This has been a bad year for terrorists."