SANAA: Here is a timeline of the conflict in Yemen since a Saudi-led military coalition intervened in March 2015 to stop the advance of the Iran-backed Huthi rebels.
The Huthis on Tuesday said they had fired a ballistic missile into Saudi Arabia aimed at the king's residence in the capital, as Riyadh announced it had intercepted it.
Yemen is the scene of the world's worst humanitarian crisis, and millions of people there are directly threatened by famine, according to the United Nations.
The war has claimed more than 8,750 lives and left tens of thousands injured. Since late April, more than 2,000 people have died of cholera.
- 'Decisive Storm' -
On March 26, 2015, a coalition of nine countries led by Riyadh launches operation "Decisive Storm" with air strikes on the rebels to defend embattled President Abedrabbo Mansour Hadi, who seeks shelter in Riyadh.
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.
In July 2015, the government announces they have retaken the southern province of Aden from rebel control. 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 five southern provinces.
But they face a growing presence of jihadist fighters from Al-Qaeda and the Islamic State group.
In October 2015, government forces retake control of the strategic Bab al-Mandab Strait, through which much of the world's maritime transport transits.
In January 2017, pro-government troops backed by coalition planes and ships launch operation "Golden Spear", as they seek to retake areas along the Red Sea.
- Carnage -
On September 28, 2015, the coalition is accused of hitting a wedding hall in the southwestern coastal town of Mokha in an air strike, killing 131 people. The coalition denies responsibility.
On August 15, 2016, it bombs the hospital in the northwestern town of Abs, the fourth strike to hit a building housing aid group Medecins sans Frontieres (Doctors without Borders) in a year.
On October 8, 2016, a coalition air strike at a funeral ceremony in Sanaa kills 140 people and wounds more than 500.
The coalition has been regularly criticised for errors during its air strikes that have caused civilian casualties.
- War crimes -
In June 2017, Human Rights Watch accuses the United Arab Emirates -- a member of the Saudi-led coalition -- of operating at least two informal detention facilities in Yemen. Abu Dhabi denies the accusation.
In late September, the UN Human Rights Council agrees to send war crimes investigators to Yemen.
- Saleh killed by former allies -
The Huthis in August 23, 2017 call former president Ali Abdullah Saleh a "traitor" after he dismissed the group as a "militia" in a speech.
Violence erupts between the former allies on November 29 in Sanaa, killing and wounding dozens.
On December 4, Saleh, who has reached out to the Saudi-led coalition, is killed by Huthi fighters, who strengthen their grip on Sanaa.
- Missiles on Riyadh -
On November 4, 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.
Saudi Arabia accuses Iran of "blatant military aggression" through its support of the rebels.
On November 6, the coalition shuts down Yemen's borders and halts aid deliveries in response.
On December 14, the US ambassador to the United Nations, Nikki Haley, says the missile was made in Iran. Tehran accuses Washington of trying to divert attention from its own responsibility for the war.
On December 19, Saudi Arabia says it intercepted another missile over Riyadh fired by the Huthis, who announced the target was the official residence of King Salman.