What you need to know:
The country has been mired in a deadly conflict between troops loyal to President Abedrabbo Mansour Hadi and Shiite Huthi rebels
The violence has since has killed nearly 10,000 people and triggered what the United Nations has described as the world's worst humanitarian crisis
Huthi rebels have opposed the government for the past decade and are backed by Iran, which denies military involvement
- Several raids blamed on government forces, backed by Saudi and Emirati forces, have killed many civilians
Yemen, an impoverished country on the Arabian peninsula, has been mired in a deadly conflict between troops loyal to President Abedrabbo Mansour Hadi and Shiite Huthi rebels since 2014.
The conflict escalated in 2015 after a Saudi-led coalition launched military operations in Yemen, helping the government to push back against rebels who had seized the capital and several provinces.
The violence has since has killed nearly 10,000 people and triggered what the United Nations has described as the world's worst humanitarian crisis.
Here's a timeline of key events:
In July 2014, Huthis, who come from a branch of Shiite Islam and consider themselves sidelined after the 2011 uprising against former president Ali Abdullah Saleh, launch an offensive from their northern stronghold of Saada.
They have opposed the government for the past decade and are backed by Iran, which denies military involvement.
In September, the rebels, allied to military units who have remained loyal to Saleh, enter the capital Sanaa.
They seize government headquarters and state radio after several days of fighting.
In October they seize the Red Sea port of Hodeida, then move towards the centre of the country.
On January 20, 2015, after two days of deadly fighting, the Huthis seize the presidential palace in Sanaa and surround the residence of Hadi, who flees south to Aden a month later.
A Saudi-led coalition launches air strikes on the rebels in March 2015 to counter their advance on the south.
Hadi takes refuge in the Saudi capital Riyadh.
In July, Hadi's embattled administration announces its forces have retaken the southern province of Aden in their first success since the coalition stepped in.
Aden becomes the country's de facto capital.
By mid-August, loyalist forces have retaken five southern provinces, but struggle to secure them due to the presence of Al-Qaeda's Yemen branch and the Islamic State group.
In October, government forces reclaim control of the Bab al-Mandab Strait, one of the world's busiest and most strategically sensitive shipping routes.
In August 2016 UN-brokered negotiations in Kuwait between the government and rebels break down on several points, notably the withdrawal of rebels from several strategic towns and power sharing with the government.
ALI ABDULLAH SALEH
Splits emerge in the rebel camp in 2017, resulting in violent clashes and the assassination of Hadi's predecessor and former Huthi ally, Saleh, by rebel fighters in December.
The rebels strengthen their grip on the capital.
Splits also emerge in the government camp, with fierce clashes erupting in Aden in January 2018 between southern separatists and fighters loyal to Hadi.
In December 2017, government forces make a breakthrough in efforts to reconquer the key port of Hodeida when they drive Huthi fighters out of a town en route called Khokha.
Hodeida is a vital entry point for the bulk of the country's food and aid.
On June 13, 2018 government fighters, backed by Saudi and Emirati forces, launch an offensive on Hodeida city.
On June 20, they say that they have taken control of Hodeida airport on the southern outskirts.
Civilians, in particular children, have paid a heavy price during the conflict.
Several raids blamed on the coalition have killed civilians, including on a wedding hall in the town of Mokha in September 2015, killing 131 people. The coalition denies responsibility.
In October 2016, a coalition air strike at a funeral in Sanaa kills 140 people.
On August 9, 51 people, including 40 children, are killed in an attack on a bus in rebel-held northern Yemen.
The coalition admits that "mistakes" were made but insists the target was "legitimate".
On August 23, a further 26 children are killed by coalition air strikes.
Days later, UN investigators highlighted possible war crimes in Yemen.