The conflict in Yemen between the Iran-backed Houthi rebels and pro-government troops escalated in March 2015 when a Saudi-led military coalition intervened in support of the loyalists.

The civil war has killed more than 370,000 people, directly and indirectly, according to the United Nations.

The conflict shows no signs of abating and the country teeters on the edge of famine.

Humanitarian crisis

The UN describes the situation in Yemen as the world's worst humanitarian crisis.

Around 80% of its 30 million people depend on some form of aid for survival, but the UN warns aid agencies are being forced to slash "life-saving" programmes due to a shortfall in funding.

A UN donor conference on March 16, 2022 raises only $1.3 billion in funding for Yemen, despite seeking $4.27 billion.

UN agencies warn that up to 19 million people could need food assistance in the second half of 2022, with the number of people starving in famine conditions projected to increase five-fold over the year to 161,000.

Aid agencies are running out of funds and are forced to slash "life-saving" programmes.

Oxfam said this week that more than 24,000 air strikes since the coalition's intervention have damaged 40% of all housing in Yemen's cities.

Save the Children said up to 60% of children in Yemen know someone who has been maimed in the conflict, with the Norwegian Refugee Council saying that "millions of children struggle to sleep at night, suffering extreme hunger".

Children in a bomb-damaged school in Taez

2015: Saudi steps in

Houthi fighters from the Zaidi Shia minority, which had opposed the central government for a decade, launch an offensive in mid-2014, seizing swathes of territory.

Their conquests include the capital Sanaa and the Red Sea port of Hodeida, a crucial entry point for imports and humanitarian aid.

The Saudi-led coalition comes to the embattled government's aid on 26 March 2015, launching air strikes on the rebels.

The intervention is requested by Yemeni President Abedrabbo Mansour Hadi, resident in the southern city of Aden after the Houthi takeover of Sanaa.

The United States says it is contributing logistics and intelligence to the coalition.

Initial coalition wins

On 27 March, the coalition says it has full control of Yemen's airspace and has destroyed aircraft seized by the Houthis.

As the rebels advance on Aden, Mr Hadi flees, first to Oman and then Saudi Arabia.

But the coalition helps pro-government forces secure Aden, which becomes the government's interim capital, with Sanaa still under rebel control.

In October, pro-government forces announce they have retaken control of the Bab al-Mandab Strait, one of the world's most strategic waterways.

2018: Battle for key port

In June 2018, pro-government fighters, backed by Saudi and Emirati ground forces, launch an offensive to retake Hodeida, the entry point for 90% of Yemen's imports.

UN-brokered talks in Sweden between the government and Houthi rebels open in December, yielding breakthroughs, including a ceasefire in Hodeida.

However, fighting continues intermittently.

The aftermath of a Saudi-led alliance air strike on Sanaa

2019: Saudi oil hit

In September 2019, aerial assaults claimed by the Houthis on two facilities run by energy giant Aramco in eastern Saudi Arabia temporarily knock out half of the kingdom's crude production.

Riyadh and Washington accuse Iran of being behind the attack, which it denies.

Saudi Arabia's oil infrastructure is again hit in March 2022, when a Houthi drone attack on an Aramco facility in the west of the country results in a "temporary reduction" in output.

2021: New escalation

In early 2021, the Houthis resume an offensive to seize oil-rich Marib province, the government's last northern stronghold, as well as intensifying drone attacks against Saudi Arabia.

The upsurge in violence coincides with Washington ending its support for coalition military operations and removing the Houthis from a blacklist of "terrorist" organisations.

2022: Rebels turn on UAE

The United Arab Emirates, which announced a withdrawal of its troops from Yemen in 2019 but is still part of the Saudi-led coalition, is hit by a Houthi drone-and-missile assault on January 17, 2022.

The attack, which killed three oil workers in the capital Abu Dhabi, is the first deadly assault on the UAE claimed by the rebels and is the first in a series of attacks.

The US announces in February it is sending the guided missile destroyer USS Cole and fighter jets to Abu Dhabi to bolster its defences.