After a violent Wednesday that saw 17 protesters killed, soldiers loyal to President Ali Abdullah Saleh and defectors clashed in the streets of Sanaa, leaving a number wounded. It may have been the first shots in a much bigger battle.
That is because in the wake of attacks on student protesters, a number of calls went out for protection. This has led several hundred Yemeni tribesmen, many of them leaders of enormously influential factions, to answer the call.
Though it is only a few hundred tribesmen now, the fiercely loyal and heavily armed tribes would clearly react with overwhelming force if the Saleh government crackdown got several of them killed.
Indeed, past attempts at crackdowns in the north spawned violent retaliation from the tribes there. This ended with the northern provinces in a state of de facto independence. If the new deployments end in a similar manner, it could cost Saleh control over what little of the nation he has left.