The US president says he is worried Yemen is drawing foreign terrorists who once may have gone to Pakistan's border, after a suicide bomber killed more than 90 soldiers in Sanaa.
A double agent allegedly recruited by MI5 and MI6 was a British passport holder, according to American media reports.
An undercover agent who foiled an al-Qaeda plot to blow up a airliner with an underwear bomb is a British national, according to US reports.
A would-be underwear bomber foiled by American intelligence is actually a double agent, according to US reports.
Channel 4 News looks at the al-Qaeda group in the Arabian Peninsula linked to explosives found on two cargo planes, and Public Enemy No 1 for the UK intelligence services, Anwar al-Awlaki.
US officials say the discovery of a plot involving an improved "underwear bomb" shows militants are determined to build bombs that can pass through airport security.
America foils a plot by al-Qaeda in Yemen to detonate an upgraded version of the failed 2009 "underwear bomb", according to US officials.
Khalid Sheikh Mohammed and four others who say they planned the 9/11 attacks on New York and Washington appear in a military court charged with murdering 2,976 people.
The publication online of documents seized at Osama bin Laden's house underlines the gulf between western and jihadi thinking.
A car bomb explodes outside a compound housing Westerners in Kabul hours after US President Barack Obama visits the Afghan capital.