Please check out the following link which might help you to get some ideas:

http://www.e-ir.info/2015/05/20/saudi-airstrikes-on-yemen-limits-to-military-adventurism/ 

The attack of Saudi Arabia and other countries against Yemen has no direct relationship with the nuclear power in Iran, but with the country. The root of the fight is religious. Iran is dominated by Shiites and Saudi Arabia by Sunnis, two of the main branches of the Islam that have a very long history of confrontation. The Shiites forces in Yemen took of the control of the government and of a big part of the country and Saudi Arabia and other countries are trying to impede that the Shiites forces take definitely the control of the country. If this happens then Iran will reinforce its position in the region, something that Saudi Arabia is totally again.

The origins of the conflict date back to 2004 (June). Saudi Arabia led a coalition of Arab states attacked Yemen for religious reasons. Saudi Arabia (Sunni) influence prevents the growth of Shiites in Yemen. Shiites in Yemen are supported by Iran (Shiite). Strengthening the Shiites in Yemen will lead to an increase in the role and importance of Iran in the region, to which not want to let Saudi Arabia.

to prof. Jan A. Wendt, the International Crises Group in report about Yemen, declared that isn't any document show the military support of shiite groups by Iran. do you believe that?

There are another more or less independent reports, which underline high level of possibilities such situation. Too many random events with the participation of Iran in order to be able to be uninvolved. Another, different example: we repeat the President of Russia, Vladimir Putin, that Russia is not a party and is not involved militarily in the conflict in eastern Ukraine. The old Latin maxim "cui bono?" can help you find the answer.

It is clear that the nature of the conflict is religious, but maybe the key to understand the conflict is the shift in the balance of power in the Middle East, with the increasing role of Iran (the Shia crescent, now strongly present in Damascus, Beirut, Baghdad and Sanaa) and the consequent reaction of the Saudi-Egyptian group. Also, it is worth knowing that the United States and Iran, while sealing an agreement on the nuclear, are fighting in opposed coalitions in Yemen.

Although every one is trying to reflect the war in Yemen as a religious matter, Saudi war on Yemen is not for reliougiois reason. The conflict goes back centuries ago. Saud family raided Yemen many times since the eighteenth century, Saudis occupied Tehama valley, Asir, Jizan,  which were the  Yemeni  province of the Idrisis, in 1924-34 war. The Idrisisis joined the king of Yemen in Sanaa Imamm Yahya Hamid al-Din against Al-Saud. The Saudiis with their allies reached Hodaidah, a main Yemeni port on the Red Sea coastal. The War between Saudis and Yemen ended in 1934 with the treaty of Taif, which stated that Saudi Arabia has to return the occupied Yemeni land to Yemen. After 60 years Saudi Arabia didn't fulfill the treaty and refused to return the rented land to Yemen. In the 1962 Saudi Arabia supported the Mutwakel royal family in the of North Yemen against the republic leaders. The royal family fled to the north border with Saudi Arabia and collected support from the Shia Houthi tribes against the republican. Yemen 1962-70 became a battle field between royal family supported by Saudi Arabia, Jordan, and the British covert support on one hand and the republic founders supported by Naser and USSR on the other hand. 1994 another civil war between north and south took place. It is the same year in which Saudi Arabia should return the land to Yemen. The conflict between north and south Yemen reached its climax when Saudiis supported the south ex-president who was Vice President after the Union Ali Salem al-Beed. He allied himself to Saudi family and fled to Saudi Arabia during the war and reside there. Saudi Arabia interfered many times through its allies especially the AL-Ahmar family in the internal affairs in Yemen. Al-Ahmar a defencThe  Hauthis were marginalized for long time from the government. Their territories were left behind and they were on their own before 1994. Beside Economic and strategic interest in Yemen Saudi Arabia had a feeling of insecurity, fear and jealousy .  It's war on Yemen can be interpreted as "Jealousy",  a protective reaction to a perceived threat to a valued relationship. The negotiations between the United States and Iran distrrubed the Saudis-American relations. Yemen again became a battle field between the regional powers and their supporters. 

Re Anahid Huth's remark "protective reaction to a perceived threat," the following article throws some light on that. For example, the issue is not only whether or not to attack someone, but whether to attack someone now or later dependent on e.g. perceptions of whether a threat (which may be of any kind; religion, terror, culture, ideology, values, etc.) will increase or decrease.

Hausken, K. (2008), “Whether to Attack a Terrorist’s Resource Stock Today or Tomorrow,” Games and Economic Behavior 64, 2, 548–564.

Article Whether to attack a terrorist's resource stock today or tomorrow