War in Yemen, the poorest Arab nation: who are Houthis and why is Saudi coalition fighting them

Yemen, the poorest country among Arab nations, is once again in the spotlight after drone strikes in Emirates capital Abu Dhabi were followed by Saudi Arabia-led coalition carrying out strikes on the militant Houthi group.

Yemen's war began in September 2014, when the Houthis, who are Shias, seized Sanaa and began a march south to try to seize the entire country. Saudi Arabia, along with the UAE, both of whom are Sunni majority, and other countries, entered the war alongside Yemen's internationally recognised government in March 2015.

Situated along the southern tip of the Arabian Peninsula, Yemen had been split in the Cold War between a Marxist south and a northern republic. The two nations became a unified Yemen in 1990, fought a civil war in 1994 and later came under the rule of Ali Abdullah Saleh. During the Arab Spring protests, Saleh began losing his grip on power and ultimately agreed to let his vice president, Abed Rabbo Mansour Hadi, take over. However, Hadi's government struggled and Saleh, seeing a second chance to regain power, had his forces side with the same Houthis as they swept into the capital in 2014.

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Iran, which is a Shia majority, seeing the opportunity to aid a war of attrition against its regional rival, Saudi Arabia, backed the Houthis. Arab countries, the West and United Nations experts say Iran has armed the Houthis with everything from assault rifles to ballistic missiles.

Saudi Arabia and its Gulf Arab allies fear the Houthis could grow as powerful as Lebanon's Shia Hezbollah militant group. The Houthis have already launched drone and missile attacks deep into the kingdom before, and on occasions struck oil wells.

All the while, Yemen's issues such as endemic poverty, lack of water and other resources have worsened. The war merely compounded the misery, and the country of 29 million people is now on the brink of famine.

The war has killed some 233,000 people, including 131,000 from indirect causes such as lack of food, health services and infrastructure, according to the United Nations.

The aid group, Save the Children, estimates that 85,000 children under the age of five have died from starvation or disease since the war began.