In Egypt and Tunisia, the stance of the military was pivotal in the success of popular uprisings;  in Yemen, it may be the tribes that are the determining factor. 

Anti-government protests across Yemen show no signs of abating. In Taiz, Yemen's largest governorate, many who arrived last Friday are still in the city center a week later. Their numbers have grown as citizens from outside the city center have joined the sit-in demanding the ouster of President Ali Abdullah Saleh.  A grenade attack today injured eight.

In Aden, security forces were reported shooting from rooftops. Four protesters were killed by gun fire this week and dozens injured.  Demonstrations against President Ali Abdullah Saleh, in power since 1978, were also held in Hodiedah, Hadramout, Dhalie, Abyan, Ibb, al Beidha. Lahj and other governorates. The protests in the capital, Sana'a have gained the most international attention, because thats where the reporters are. In Sanaa, the state deployed deniable proxies, supposed pro-government protesters, to attack democracy activists with clubs and knives.