A Saudi-led Arab coalition launched a military operation in Yemen three years ago coming to the aid of a government struggling against rebels who had seized the capital Sanaa.
The intervention helped the government claw back some territory but the war has only become more complicated, with Amnesty International saying both sides are potentially responsible for war crimes.
The conflict has killed nearly 10,000 people in impoverished Yemen, triggering what the United Nations has called the world's worst current humanitarian crisis.
- Operation launched -
In March 2015, a coalition of nine Arab countries led by Riyadh begins an operation in support of President Abedrabbo Mansour Hadi with air strikes on Shiite Huthi rebels, who control Sanaa and large swathes of northern, central and western Yemen.
In July, the embattled government announces it has retaken the southern province of Aden in its first success since the coalition stepped in.
The coalition supplements its air power with hundreds of ground troops and by mid-August 2015 loyalist forces have retaken five southern provinces.
In October, government forces retake control of the Bab al-Mandab Strait, one of the world's busiest shipping routes.
- 'War crimes' -
Over the following months, the coalition is regularly criticised over its air strikes, including hits on markets and hospitals that cause heavy civilian casualties.
In September 2015, it is accused of hitting a wedding hall in the southwestern coastal town of Mokha in an air strike, killing 131 people. It denies responsibility.
And in October 2016, a coalition air strike at a funeral ceremony in Sanaa kills 140 people and wounds more than 500.
Earlier this month, Amnesty says it has documented 36 coalition attacks in which 513 civilians were killed, "many of which may amount to war crimes".
It also slams the rebels for potential war crimes, including indiscriminate artillery shelling, enforced disappearances and death sentences against dissidents.
- Rebels kill ex-president -
Splits emerge in the rebel camp in 2017, resulting in the assassination of Hadi's predecessor Ali Abdullah Saleh, who had stepped down in 2011 after ruling Yemen with an iron fist for nearly three decades.
The Huthis in August call their former ally in Yemen's revolt, Saleh, a traitor when he dismisses the group as a militia in a speech and reaches out to Saudi Arabia.
Violence erupts between the former allies in November in Sanaa, killing and wounding dozens, and Saleh is killed by Huthi fighters in December.
- Missiles on Riyadh -
In November 2017, Huthi rebels fire a missile in the direction of the international airport in Riyadh.
Intercepted and destroyed, it is the first to reach the Saudi capital and enrages Saudi Arabia which accuses its arch-foe Iran of "blatant military aggression" through its support for the rebels.
Iran denies supplying then with weapons.
The coalition tightens its control of Yemen's borders, only partly easing the blockade after warnings of the impact on desperately needed food and humanitarian aid deliveries.
Two other missiles are intercepted over Riyadh fired by the Huthis, who say the target was the official residence of Saudi King Salman.
- Splits in government camp -
On January 28, 2018, fierce clashes erupt in the port city of Aden, the de facto capital after the capture of Sanaa, between military units loyal to Hadi and southern separatists.
The separatists, who are backed by the UAE, a key member of the coalition, seize most of the city.