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 adviser.
The
main fight is between forces loyal to the beleaguered President, Abdrabbuh
Mansour Hadi, and those allied to Zaidi Shia rebels known as Houthis, who
forced Mr Hadi to flee the capital Sanaa in February.
Yemen's
security forces have split loyalties, with some units backing Mr Hadi, and
others the Houthis and Mr Hadi's predecessor Ali Abdullah Saleh, who has
remained politically influential. Mr Hadi is also supported in the
predominantly Sunni south of the country by militia known as Popular Resistance
Committees and local tribesmen.
Both
President Hadi and the Houthis are opposed by 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 jihadist group Islamic State, which seeks to eclipse AQAP and
claims it carried out a series of suicide bombings in Sanaa in March 2015.
After
rebel forces closed in on the president's southern stronghold of Aden in late
March, a coalition led by Saudi Arabia responded to a request by Mr Hadi to
intervene and launched air strikes on Houthi targets. The coalition comprises
five Gulf Arab states and Jordan, Egypt, Morocco and Sudan.
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 been carrying
out operations, including drone strikes, against AQAP in Yemen with President
Hadi's co-operation, but the Houthis' advance has meant the US campaign has
been scaled back.
The
conflict between the Houthis and the elected government is also seen as part of
a regional power struggle between Shia-ruled Iran and Sunni-ruled Saudi Arabia,
which shares a long border with Yemen.
Gulf
Arab states have accused Iran of backing the Houthis financially and
militarily, though Iran has denied this, and they are themselves 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.
In
short, after months of tightening their hold, the Houthis have formally seized
power. In January, the group said it would dissolve parliament and announced
plans for a new interim assembly and five-member presidential council, which
would rule for up to two years.
The
move filled a political vacuum which had existed since President Hadi, the
prime minister and cabinet resigned earlier that month 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 tribesmen 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 declared the de facto capital.
The
Houthis are members of a rebel group, also known as Ansar Allah (Partisans of
God), who adhere to a branch of Shia Islam known as Zaidism. Zaidis make up
one-third of the population and ruled North Yemen under a system known as the
imamate for almost 1,000 years until 1962.
The
Houthis take their name from Hussein Badr al-Din al-Houthi. He led the group's
first uprising in 2004 in an effort to win greater autonomy for their heartland
of Saada province, and also to protect Zaidi religious and cultural traditions
from perceived encroachment by Sunni Islamists.
After
Houthi was killed by the Yemeni military in late 2004, his family took charge
and led another five rebellions before a ceasefire was signed with the
government in 2010.
In
2011, the Houthis joined the protests against then President Saleh and took
advantage of the power vacuum to expand their territorial control in Saada and
neighbouring Amran province.
They
subsequently participated in a National Dialogue Conference (NDC), which led to
President Hadi announcing plans in February 2014 for Yemen to become a
federation of six regions.
The
Houthis however opposed the plan, which they said would leave them weakened.
In
recent years Yemen has seen violent conflicts largely caused by underlying
problems of unequal access to power and resources.
There
have been six rounds of fighting between the state and the Houthis in the
north; separatist unrest in the south; frequent attacks by AQAP; and power
struggles between tribal and military factions.
For
much of the 20th Century, Yemen existed as two separate countries - the Yemen
Arab Republic (YAR) in the north and the People's Democratic Republic of Yemen
(PDRY) in the south. In 1990, the countries chose to unify and create the
Republic of Yemen. However, southerners soon began complaining of political and
economic marginalisation by the government in Sanaa, and fought a civil war in
1994 in a failed attempt to reverse the unification.
Instability
and large-scale displacement, as well as weak governance, corruption, resource
depletion and poor infrastructure, have hindered development in the poorest
country in the Middle East.
