Probably led by those many al-Qaeda members Yemen [1] recently released. "Saudi Officials' Fears: Al-Qaeda Planning to Attack Saudi Arabia from Yemen," by Sahar Al-Sharjabi for the [2] Yemen Post, April 26 :

A British newspaper quoted General Mansoor Al-Turki, the spokesman for the Saudi Ministry of Interior, as speaking about his fears regarding Al-Qaeda. The Financial newspaper wrote that Saudi Arabian officials fear that Al-Qaeda is planning to attack their country from Yemen that they could not do that from inside.

Al-Qaeda has changed its name to 'Al-Qaeda in the Arabian Peninsula' to bring together the extremist Saudis those [who] ran away from their country and the armed Yemenis the newspaper reported...