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.
More than 90 people were killed and 222 injured when a suicide bomber attacked soldiers practising for a military parade in Sanaa, the Yemen capital.
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.
Defence analyst Anthony Tucker-Jones assesses where conflicts are most likely to erupt over the next 12 months.
Forces loyal to Yemeni President Ali Abdullah Saleh fire in the air to stop tens of thousands of protesters, who are demanding he face trial, approaching his compound.
The first Arab woman to win the Nobel Peace Prize wants Britain to freeze President Saleh's assets, and tells Channel 4 News she was laughed at for protesting - until the Tunisian revolution.
The man accused of trying to blow up a US airliner on Christmas day 2009 by detonating a bomb in his underpants pleads guilty to all charges against him.
As a US drone strike in Yemen kills cleric Anwar al-Awlaki, a leading al-Qaeda figure, Channel 4 News assesses his influence on terror attacks in the UK and abroad.
The Seychelles government hits back at allegations the US is using the islands to launch drone attacks in Somalia and Yemen, insisting the aircraft are monitoring pirates not terrorists.