By ALISSA J. RUBIN and KAREEM FAHIMThe Saudi foreign minister said the five-day cease-fire could be renewed, and called upon Houthi rebels to “come to their senses.”
The Saudi bombing campaign, brutal beyond measure, has made the now more-fundamentalist Saud family less safe and therefore more fearful and brutal.
That is the way human animals work.
The Saudi have now increased the likelihood o f unrest among the Shia in their oil-rich Eastern Province, where there has been violence in the recent past.

To give you the flavor of the relationship, here is a quotation from the Wikipedia article:
In 1997, Saudi official Sheik Ali Khursan declared Ismaelis (the Shia who live closest to the Houthi) to be infidels because they did not follow the Sunna and do not believe that the Qur'an is complete, stating `We don't eat their food, we don't intermarry with them, we should not pray for their dead or allow them to be buried in our cemeteries.`
Reminds one of some attitudes in some parts of the US, sadly. According to Vali Naasr, that attitude from Sunni toward Shia is common.
For a brief history of the Sunni-Shia relations in the Arabian Peninsula, see the Wikipedia article reprinted after the jump.