Editor's note: Peter Bergen is CNN's national security analyst, a director at the New America Foundation and the author of "Manhunt: The Ten-Year Search for bin Laden -- From 9/11 to Abbottabad." Jennifer Rowland is a program associate at the New America Foundation.
(CNN) -- On Wednesday, al Qaeda's virulent Yemeni affiliate which is known as al Qaeda in the Arabian Peninsula (AQAP) confirmed the death of the group's deputy leader and co-founder, Saeed al-Shihri, in a video message posted to jihadist websites.
It was a confirmation of what was long suspected: that Shihri was killed in a U.S. drone strike several months ago. And it also amounted to a concession that the al Qaeda affiliate is under an enormous amount of pressure.
In the past three years more than 30 al Qaeda leaders and other senior operatives in Yemen have been killed by U.S. drone strikes, according to a count by the New America Foundation.
The militants killed by those drone strikes included Anwar al-Awlaki, the fiery Yemeni-American preacher who served as a key ideologue for the group and has been an inspiration for a wide range of militants living in the West, including the Tsarnaev brothers who are accused of bombing the Boston Marathon in April.
Not all of the drone strikes in Yemen have found their targets. New America Foundation's review of reliable media reporting of those strikes found that somewhere between 38 and 71 of the casualties were civilians, which included Awlaki's 16-year-old son.
A Yemeni tribal leader close to AQAP says the drone strikes have sown mistrust within the group, where there is "a feeling that the Americans have infiltrated its ranks, especially with the killing of several of its leaders."
Al-Shihri, a Saudi who spent six years at the Guantanamo Bay detention facility, was first reported killed in January. The Yemeni government quickly confirmed Shihri's death, but until now AQAP had denied it.
AQAP's video message confirming Shihri's death was delivered by Ibrahim al-Rubaish, another Saudi who was also formerly held at Guantanamo Bay.
In the 11½-minute video, which we have reviewed, Rubaish gushes about Shihri's devotion to al Qaeda's cause. Rubaish says Shihri was "searching for martyrdom," trumpeting his combat against U.S. forces in Afghanistan where he suffered serious injuries to his hands and legs, and lost an eye.
Shihri was released from Guantanamo in November 2007, and entered a Saudi rehabilitation program and was then released. Rubaish says Shihri subsequently planned an attack on the U.S. Embassy in the Yemeni capital, Sanaa, which killed 10 Yemeni policemen and civilians.
But Shihri grew complacent. "Lax security measures during his telephone calls enabled the enemy to identify and kill him," Rubaish declared in his eulogy.
Shihri's death in the U.S. drone strike is part of larger story of AQAP decline over the past two years. In 2011, AQAP had gained significant territory in Yemen as it exploited the popular uprising against longtime Yemeni president Ali Abdullah Saleh. Its core membership grew from approximately 300 members in 2009 to around 1,000 three years later, according to Gregory Johnsen, the author of the authoritative book "The Last Refuge: Yemen, al-Qaeda, and America's War in Arabia".
But the jihadist group lost all of these gains within about a year. An offensive by the Yemeni army that was supported by U.S. intelligence last year pushed AQAP out of the central Yemeni province of Abyan, forcing AQAP's fighters to flee to the remote desert province of Hadramaut.
The group has since been reduced to carrying out much smaller attacks; nothing compared to the massive suicide bombing it was able to conduct in the heart of the Yemeni capital in May 2012, which killed upwards of 100 soldiers as they rehearsed for a military parade.
And despite its focus on attacking U.S. targets, AQAP has not tried to attack one since its October 2010 attempt to plant bombs hidden in printer cartridges on cargo planes destined for the United States. (Last year AQAP plotted to send an operative with explosives in his underwear aboard a plane bound for the United States, but that operative was actually secretly working for the British and Saudi intelligence services, so the plot was never a real threat.)
Despite all the losses AQAP has suffered its capable chief bomb maker, Ibrahim al-Asiri, remains at large. Al-Asiri was the brains behind AQAP's failed "underwear bomb" attempt to bring down a Detroit-bound U.S. airliner on Christmas Day 2009.
AQAP's overall leader, Nasser al-Wuhayshi also remains at large, Wuhayshi is AQAP's founder and his continued survival is surely important for the organization.
AQAP could regenerate, particularly if Yemen sees more upheaval, but for now, the group is on the run from the Yemeni army and U.S. drone strikes, fearful of spies in its midst, is unable to launch large-scale attacks, and boasts a dwindling cadre of leaders. AQAP, in short, is struggling to survive.
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