Yemen is in the grip of its most severe crisis in years, as competing forces fight for control of the country. Impoverished but strategically important, the tussle for power in Yemen has serious implications for the region and the security of the West. Here are some key questions explained. Who is fighting whom? In recent months Yemen has descended into conflicts between several different groups, pushing the country "to the edge of civil war", according to the UN's special envoy. The president, Abdrabbuh Mansour Hadi, fled to his southern stronghold of Aden after being ousted from the capital, Sanaa. Backed by military and police loyalists, and by militia known as Popular Resistance Committees, he is trying to fight off forces allied to Shia rebels known as Houthis. The Houthis, supported by elements in the security forces and backed by President Hadi's predecessor Ali Abdullah Saleh and Iran, stormed Sanaa in September and have since expanded their control over other parts of the country. Both President Hadi and the Houthis are opposed by al-Qaeda's local affiliate, al-Qaeda in the Arabian Peninsula (AQAP), which has staged numerous deadly attacks from its strongholds in the south and south-east. The picture is further complicated by the emergence in late 2014 of a Yemen affiliate of the militant group Islamic State, which propounds an extreme version of Sunni Islam and seeks to eclipse AQAP. In March, IS said it carried out bombings on two mosques in Sanaa, which killed some 140 people in one of the deadliest attacks in Yemen's history. What does Islamic State want with Yemen? Why does it matter for the rest of the world? What happens in Yemen can greatly exacerbate regional tensions. It also worries the West because of the threat of attacks emanating from the country as it becomes more unstable. Western intelligence agencies consider AQAP the most dangerous branch of al-Qaeda because of its technical expertise and global reach. The US has long been carrying operations against AQAP in Yemen with President Hadi's co-operation, but his ousting could make the campaign more difficult. The conflict between the Houthis and the elected government is also seen as part of a regional power struggle between Iran and Sunni Saudi Arabia. Shia Iran backs the Houthis (though to what extent is unclear), while Saudi Arabia, which shares a border with Yemen, and the Gulf state, are strong backers of President Hadi. Yemen is strategically important because it sits on the Bab al-Mandab Strait, a narrow waterway linking the Red Sea with the Gulf of Aden, through which much of the world's oil shipments pass. Egypt and Saudi Arabia fear a Houthi takeover would threaten free passage through the strait. How did it all get out of control? In short, after months of tightening their hold, the Houthis have formally taken power. The group has dissolved parliament and announced plans for a new interim assembly and five-member presidential council, which will rule for up to two years. The move filled a political vacuum which had existed since President Hadi, the prime minister and cabinet resigned in January after the Houthis placed President Hadi under house arrest and detained other leading figures. But the Houthis are minority Shia from the north, and their declaration has not been recognised by Sunni and southern leaders, threatening Yemen with a further descent into chaos. President Hadi, who is recognised as Yemen's legitimate leader by the international community, managed to escape to Aden, which he has declared the de facto capital. Source: BBC
