One theory of the Yemeni conflict

"Saleh is getting old and is probably tired. He is grooming his son to replace him. Ali Muhsin considers himself to be the more deserving than Saleh's son, especially that the latter has zero popularity and charisma and no one would recognize him in the street without his motorcade. So whenever Muhsin wants to put pressure on Saleh, he commands the army to engage the Hawthi who are always ready for a fight. As long as the fighting goes on, Saleh is under popular pressure." (thanks Rami)