More than 250 people died in the 1998 attacks on US embassies in Kenya and Tanzania, for which al-Qaeda claimed responsibility.
More than 250 people died in the 1998 attacks
The US also holds the same cell responsible for attacks on an Israeli aircraft and Israeli-owned hotel in Kenya in 2002, in which 15 people died.
Few details about key figures have been officially released. BBC News Online pieces together what little is known about three of the suspects.
FAZUL ABDULLAH MOHAMMED
There are unconfirmed reports that Fazul Abdullah Mohammed was killed in a recent US air strike in southern Somalia, according to a US intelligence report passed on to the Somali authorities.
Mohammed allegedly trained with Osama bin Laden in Afghanistan
Mohammed, 32, from the Comoro Islands, was allegedly being harboured by Somali Islamist militants, who have challenged the country's Ethiopian-backed transitional government for power.
Mohammed joined al-Qaeda in Afghanistan and trained there with Osama bin Laden, the terror network's leader, according to the transcript of an FBI interrogation of a known associate.
He had a $5m (£2.6m) reward on his head for allegedly conspiring to bomb the US embassies in Kenya and Tanzania in 1998.
He was also suspected of planning the car bombing of a beach resort in Kenya and a near simultaneous attempt to shoot down an Israeli aircraft in 2002.
SALEH ALI SALEH NABHAN
Saleh Ali Saleh Nabhan, a Kenyan, is on an FBI wanted poster in connection with the bombing of an Israeli-owned hotel and an attempted missile attack on an Israeli airliner in Kenya in 2002.
Little is known about the 27-year-old Kenyan Nabhan
Nabhan, 27, is believed to have owned the vehicle used in the attack on the Israeli-owned hotel near Mombasa. Little else is known about him.
He is thought to be in Somalia, probably under the protection of the Islamic Courts Union.
ABU TALHA AL-SUDANI
Abu Talha al-Sudani was accused by the office of the US Director of National Intelligence recently of leading an al-Qaeda cell in East Africa.
He is also believed to be the financier of the 1998 US embassy bombings.
The Sudanese national, who has lived in Somalia since 1993, is said to be an explosives expert, having received training from Hezbollah in southern Lebanon in the early 1990s.
He is also said to be a close associate of al-Qaeda leader Osama bin Laden.