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.
Human Rights Watch reports that Shiites want to be treated as equals and desire to be free from discrimination (Human Rights Watch). However, the Shia minority is still marginalized on a large scale.
The much smaller Ismāʿīlī minority—also known asSeveners -- differ from the Twelver Shia in their acceptance of Isma'il ibn Jafar as the appointed spiritual successor (Imām), rather than Musa al-Kazim. There are an estimated 100,000 of them living in the southern region of Najran next to Yemen. They also have been subject to what Human Rights Watch calls "official discrimination," encompassing "government employment, religious practices, and the justice system".
In 1997 the director of the Ministry of Islamic Affairs opened an office in Najran for the purpose of propagating Wahhabi doctrine to the local Isma'ilis. Saudi official Sheik Ali Khursan declared Ismaelis 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.` In 1997 the Governor Prince Mish'al ordered police to prevent Ismaelis from performing prayers during the post-Ramadan Islamic festival of Eid al-Fitr. "Anti-Ismaeli campaigns resulted in many arrests and flogging." In April 2000, responding to an Amnesty International campaign publicizing lack of religious freedom in Saudi Arabia, Ismaelis in Najran openly celebrated Ashura for the first time in many years. Shortly thereafter Saudi religious police "stormed a major Ismaeli mosque, seized many of its religious texts and arrested three clerics". Local Ismaelis, who are often armed, retaliated, firing on security forces and burning some of their vehicles. Approximately 40 people were killed and many more injured. Saudi Army reinforcements swept the area and made many arrests. 
Hundreds of Ismaeli government employees were transferred away from Najran. Sometime after August 2000, four Ismaeli high school student were "sentenced to two to four years in prison and 500 to 800 lashes for fighting with a Wahhabi teacher, who openly insulted their religious beliefs in front of other students in the classroom."