The war gripping Yemen has killed around 8,650 people since a Saudi-led military intervention in 2015, and brought the impoverished country to the brink of famine.
The conflict is underscored by the regional rivalry between Iran, a supporter of Yemen's Shiite Huthi rebels, and Saudi Arabia, which heads a nine-member coalition backing the president.
Here is an overview:
- 'Decisive Storm' -
In March 26 the coalition launches operation "Decisive Storm" with airstrikes on Huthi rebels to defend embattled President Abedrabbo Mansour Hadi, who seeks shelter in Riyadh.
Besides Saudi Arabia, the Sunni coalition comprises the Gulf monarchies Bahrain, Kuwait, Qatar and the United Arab Emirates, along with Egypt, Jordan, Morocco and Sudan.
Later named "Restoring Hope", it aims to defeat the rebels who have controlled the capital since September 2014 in addition to large swathes of northern, central and western Yemen.
- Aden liberated -
In July 2015 the government announces the liberation of southern Aden province from rebel control after more than four months of fighting. It is their first success since the coalition stepped in.
The coalition supplements its air power with hundreds of ground troops and by mid-August loyalist forces have retaken the whole of the south.
However they face a growing presence of fighters from Sunni jihadists of Al-Qaeda and the Islamic State group.
In January 2017 pro-government troops backed by coalition planes and ships launch operation "Golden Spear" around the strategic Bab al-Mandab Strait, between the Red Sea and the Gulf of Aden.
- Failed ceasefires -
The UN and US organise three rounds of fruitless peace talks, in June and December 2015 in Switzerland and in April 2016 in Kuwait.
Seven truces are agreed, but all broken.
The severing in January 2016 of diplomatic relations between Saudi Arabia and Iran complicates the task.
The internationally recognised government, led by Hadi, establishes a "provisional" base in the port city of Aden in late September 2016.
Two months later, the rebels and allied forces of ex-president Ali Abdullah Saleh form a government of their own in the capital Sanaa, dousing hopes of a UN-brokered national unity government.
- Carnage -
In October 2017 the coalition is placed on a UN blacklist for killing and maiming children in the conflict.
It was in 2016 responsible for 683 child casualties and for 38 verified attacks on schools and hospitals, according to a UN report.
There have been other accusations against the coalition, including of hitting a wedding hall in Mokha in 2105 in an air strike, killing 131 people. The coalition denies responsibility.
The UN also says coalition planes have dropped banned cluster munitions and killed two times more civilians than other forces.
- Escalation -
On November 4 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.
It leads Saudi Arabia to accuse Iran of "blatant military aggression" through its support of the rebels.
The coalition shuts down Yemen's borders and halts aid deliveries in response.
Iran in turn accuses its rival of war crimes and the rebels threaten to attack ports and airports in Saudi Arabia and the United Arab Emirates.
- Famine -
The UN warns on November 8 that Yemen faces mass famine unless the coalition ends the blockade and allows aid deliveries to enter.
It could "be the largest famine the world has seen for many decades, with millions of victims," UN aid chief Mark Lowcock says.
Some seven million people are at risk of famine and an estimated 17 million -- 60 percent of the overall population -- are food insecure, according to UN figures.