Al Qaeda in the Arabian Peninsula's second in command killed, Yemen says

Yemeni forces have killed Said al-Shihri, second in command of al Qaeda in the Arabian Peninsula, the Yemeni Defense Ministry said Monday.

A Yemeni government official, speaking on condition of anonymity, said officials are waiting for DNA confirmation.

If confirmed, the death "would be a deeply significant blow against AQAP," CNN Terrorism Analyst Paul Cruickshank said.

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The killing of al-Shihri and other AQAP leaders "is leading to the gradual dismantlement of the group," CNN National Security Analyst Peter Bergen said.

White House counterterrorism adviser John Brennan in April described AQAP as "very, very dangerous" and "the most active operational franchise" of al Qaeda.

FBI Director Robert Mueller told Congress in May that al Qaeda and its affiliates, "especially al Qaeda in the Arabian Peninsula, currently represent the top counterterrorism threat to the nation."

The group was behind the so-called underwear bomb attempt on a Christmas Day U.S.-bound international flight in 2009 and an effort to smuggle bombs in printer cartridges onto U.S.-bound cargo planes in 2010.

Al-Shihri, who was once held by the United States at Guantanamo Bay in Cuba, was killed Monday in an operation in Hadramawt Valley, state-run news agency SABA reported.

Six other terrorists were killed as well, the military said in its statement, posted on an official website.

While the Yemeni military said al-Shihri was killed in "an operation by the armed forces," three local security officials told CNN that a U.S. drone conducted the strike.