Yemen is home to al Qaeda in the Arabian Peninsula, believed by many analysts to be the most dangerous affiliate of the terror network.
MORE: http://www.cnn.com/2014/02/09/world/meast/yemen-attack/index.html
See also...
Bus blast kills 2 soldiers in Yemeni capital
http://www.cnn.com/2014/02/04/world/meast/yemen-violence/index.html