U.S. officials believe there are strong historic links between Osama bin Laden's al Qaeda terrorist network and the Philippines' decade-old Abu Sayyaf rebel group, but officials aren't certain how solidly those connections have been maintained.
In recent years, Abu Sayyaf, Arabic for "Father of the Sword," has been best known for a series of high-profile kidnappings from tourist resorts in Malaysia and the Philippines believed to have netted the rebels millions of dollars in ransom payments.
The targets have included Americans and other Westerners, including Guillermo Sobero, a California man whose headless remains were found in the Philippine jungle in October. An Abu Sayyaf spokesman claimed the group beheaded him as an "independence day gift" to the nation's president. A missionary couple from Kansas seized in May along with Sobero are believed to remain in Abu Sayyaf's custody.
Some officials have seen the sudden surge of kidnappings for profit as an indication that whatever funding Abu Sayyaf may have had from al Qaeda had likely been cut off or reduced in recent years.
Although the United States is arming the Philippine military in its battle against Abu Sayyaf, and the group is on the State Department list of known terrorist organizations, Secretary of State Colin Powell has said direct U.S. military action in Southeast Asia connected to the war on terror is unlikely.
Although Abu Sayyaf appears to have been shaken up and shrunken by an intense Philippine military campaign to destroy it, some U.S. and Philippine officials believe the group's ties to al Qaeda are still in place.
"There certainly are links between al Qaeda and the Abu Sayyaf group, no doubt about it," said a U.S. official interviewed for this story.
The al Qaeda-Abu Sayyaf links are believed to go back to the origins of Abu Sayyaf. And a U.S. official recently told The Associated Press that the links continued in recent years as the two groups exchanged money, equipment and people — including Abu Sayyaf fighters being sent for training at al Qaeda camps in Afghanistan.
Roots in Afghan War
Like al Qaeda, Abu Sayyaf has its roots in the 1980s war to drive the Soviet Union from Afghanistan. Several future members of both groups — including bin Laden and future Abu Sayyaf leader Abdurajak Abubakar Janjalani — fought with Muslim mujahideen forces. Soon after the war, the nascent Abu Sayyaf offered training in combat and terrorist skills at a "university" in Pakistan.
Abu Sayyaf emerged in the Philippines in 1991 under Janjalani, an Islamic preacher from Basilan island in the southern Philippines, with an attack on a Philippine military post. Abu Sayyaf presented itself as a more radical wing of a decades-long separatist struggle by about 5 million Muslims in the southern Philippines.
However, the Philippines military and U.S. officials later said Abu Sayyaf was being funded during that early period through Mohammad Jamal Khalifa, a brother-in-law to bin Laden who was married to a Filipina and ostensibly was heading the Philippine wing of an Islamic charity.
Abu Sayyaf soon broadened its targets beyond the Philippine military to include the nation's Christian majority and, apparently, the United States.
In 1994, Abu Sayyaf claimed responsibility for a bomb aboard a Philippine Airlines flight from Manila to Tokyo that killed a passenger and injured six others.
At first, according to reports, Philippine officials did not take the claim entirely seriously, thinking Abu Sayyaf was a localized band of insurgents and criminals. However, that would soon change, as investigators learned of Abu Sayyaf connections to Ramzi Ahmed Youssef, who has since been imprisoned in the United States for the 1993 bombing of the World Trade Center, and is believed to have frequented the Abu Sayyaf school in Pakistan.
U.S. and Philippine investigators alleged Youssef, who was arrested at a Pakistan location believed to be a safe house for al Qaeda, was the master planner of the Philippine Airlines attack, as well as unsuccessful attempts to simultaneously bomb 11 American airliners over the Pacific at the same time.
Shortly after the bombing, security forces raided a Manila flat used by Youssef and found strong evidence of a plot to kill Pope John Paul II when he visited the Philippines in January 1995.
In April 1995, Abu Sayyaf made a big splash in the Philippines with a particularly brutal attack on the predominantly Christian town of Ipil, where they terrorized residents and killed more than 50.
In 1996, CIA Director John Deutch said Abu Sayyaf and another group of self-proclaimed Muslim separatists in the Philippines, the Moro Islamic Liberation Front, "may be cultivating ties with foreign terrorists."
Abu Sayyaf suffered a blow on Dec. 19, 1998, when Janjalani was killed in a gunfight with authorities. But Abu Sayyaf quickly rebounded with a fresh wave of kidnappings and raids, which have continued under new leaders including Janjalani's brother Khadafy, and military leaders known as Commander Robot and Commander Global.
The group in 2000 expanded its raids to include targets in Malaysia.
ABCNEWS' Michael S. James and John K. Cooley contributed to this report.