Based in the Yemeni tribal hinterlands but possessing global ambitions, al-Qaida in the Arabian Peninsula has become the most active and lethal of the affiliates to emerge from the shadow of Osama bin Laden's old network. Now the deadly U.S. attack on its leadership has complicated its prospects.
Some questions and answers about the group, the attack that killed the radical U.S.-born cleric Anwar al-Awlaki along with three other operatives, and the latest on al-Qaida's world franchises:
Q: What is al-Qaida in the Arabian Peninsula?
A: Formed in 2006 after two dozen al-Qaida members escaped from a Yemeni prison, the organization, then known as al-Qaida in Yemen, pulled off its biggest attack two years later. Two vehicle bombs exploded outside the U.S. Embassy compound in the capital, killing 19 people including six terrorists. This followed a period of small-arms attacks on tourists and mortar attacks against the U.S. and Italian Embassies, the presidential compound and Yemeni military fortifications.
In 2009, the organization became al-Qaida in the Arabian Peninsula, uniting Yemeni and Saudi operatives under the same umbrella and signaling its intention to serve as a hub for regional attacks against local, U.S. and other Western interests in both countries. U.S. officials say this is when the group began pursuing a global strategy.
Q: Why was the U.S. so intent on killing al-Awlaki, just one of the group's leaders?
A: They considered him the group's prime figure both in directing and inspiring plots within the U.S. They also saw him as a potent recruiter of Americans willing to carry out terrorism inside the country.
U.S. officials have said they believe al-Awlaki inspired Army psychiatrist Maj. Nidal Hasan, who is charged in the attack that killed 13 people at Fort Hood, Texas. The two exchanged as many as 20 emails, U.S. officials say. In New York, the Pakistani-American who pleaded guilty to the attempted Times Square bombing last year said he was inspired by al-Awlaki after making contact over the Internet.
They also say he assumed direct planning duties in the foiled bombing aboard a Detroit-bound airliner and in a failed attempt to crash two U.S. cargo aircraft by detonating explosives inside two packages mailed to the U.S.
"His sole purpose was to attack the U.S.," said Rep. Mike Rogers, R-Mich., chairman of the House Intelligence Committee. Rogers said al-Awlaki was "trying to devise ways around U.S. security procedures at all levels."
The death of the charismatic cleric was not the only blow to the organization's ability to spread its message _ and in English. Samir Khan, editor of the polished Jihadi online magazine and another U.S. citizen, also was killed in the assault.
Q: How did this attack differ from the raid that killed bin Laden inside his Pakistani compound?
A: Once again, the U.S. counterterrorism unit known as the Joint Special Operations Command crossed into a sovereign nation's territory to kill a wanted man. But there the similarities end.
U.S. forces flew into Pakistan and placed themselves on the ground without the foreknowledge of the Pakistani government. The drone attack on al-Awlaki's convoy unfolded with crucial assistance from Yemeni intelligence, which pinpointed and continued to monitor his location. U.S. fighter jets were also part of the mission, ready to strike quickly if the drones missed their mark, as they did the last time they targeted al-Awlaki, on May 5, just days after the bin Laden raid in Pakistan.
Why were the Yemenis so helpful? Yemeni authorities have come under increasing attack from al-Qaida in their midst and in turn have expanded their cooperation with U.S. counterterrorism operations.
The attack's command structure also was unusual, with the counterterrorism unit and the CIA working side by side, sharing intelligence and tracking and ultimately firing on the target. Both fly armed drones. The CIA directed the bin Laden raid.
Q: How much is the U.S. attack likely to hurt the capabilities of al-Qaida in the Arabian Peninsula?
A: It's too soon to know. Some intelligence officials say it should immediately cripple the organization's ability to carry out attacks on the United States, but it won't stop the movement's internal fight against the Yemeni government. Bruce Riedel, a former CIA official, called it a serious setback for the organization but not a fatal blow. "In fact al-Qaida is getting stronger every day in Yemen as the country descends into civil war and breaks apart," he said.
At least for the short term, the attack is a striking propaganda defeat for the organization, and one that crimps its ability to communicate with those in the West and recruit them.
Al-Awlaki was a galvanizing figure who could motivate Westerners to take action on their own, said Christopher Boucek, a Yemen expert at the Carnegie Endowment for International Peace. "I don't want to say he's irreplaceable, but I don't know who else could fill his shoes."
Q: What is the state of other terrorist organizations operating under the al-Qaida banner and devoted to attacking Americans and the West?
A: Yemen's al-Qaida branch may be the leading threat, but it's not the only one. The original group, now led by bin Laden successor Ayman al-Zawahiri, continues to plot and train would-be suicide attackers in Pakistan's tribal areas _ though those efforts are hampered by a barrage of CIA drone strikes.
Other splinter groups such as Africa-based al-Qaida in the Islamic Magreb, Somalia-based al-Shabaab and Boko Haram pose a "significant threat" in the African continent, but also to the United States, according to Army Gen. Carter Ham, commander of U.S. Africa Command. "Those three organizations have very explicitly and publicly voiced an intent to target Westerners and the U.S. specifically," Ham said. "I have questions about their ability to do so; I have no question about their intent to do so, and that to me is very worrying."
An even bigger concern, he said, is that the three are looking for ways to work together more closely. He said this is most apparent in efforts by al-Qaida in the Islamic Magreb, which is focused mainly on North Africa, and Boko Haram, a radical Muslim sect that wants strict Shariah law in Nigeria.
Associated Press writer Lolita Baldor contributed to this report.