I think that this Irish journalist, who has lived in the Middle East for a number of years and specialized in reporting on issues there, offers one of the best assessments of what is currently going on in Yemen.
The crisis in Yemen is the latest manifestation of the old order desperately trying to cling on to a dwindling power base. That old order has been backed by the United States and its allies among the Persian Gulf Arab dictatorships as a bulwark against a popular uprising that could lead to democratisation in the poorest Middle Eastern country. If such an outcome were to succeed, the repercussions for the autocratic Gulf monarchies would be deeply destabilising. Saudi Arabia, which shares a southern border with Yemen, is the primary concern for this spreading "instability".