Impoverished Yemen is mired in a devastating conflict between Iran-backed rebels and government forces, which intensified after Saudi Arabia led a military intervention five years ago.
Here is a broad overview:
– Arab intervention –
In September 2014, Huthi rebels from the country’s Zaid Shiite minority in northern Yemen enter Sanaa, seizing the government headquarters.
Backed by Shiite Iran, the rebels ally themselves with military units loyal to ex-president Ali Abdullah Selah, who was forced to quit after a 2011 uprising.
As well as the capital, they seize swathes of territory, including the Red Sea port of Hodeida, a crucial entry point for imports and humanitarian aid.
In February 2015, President Abedrabbo Mansour Hadi flees to the southern port of Aden.
A coalition led by Sunni-ruled Saudi Arabia, the bitter regional rival of Iran, enters the conflict on March 26, 2015 with air strikes on the rebels.
Around a dozen countries form part of the coalition, including five from the Gulf, notably the United Arab Emirates.
Washington says it contributes logistics and intelligence.
As the rebels advance southwards on Aden, Hadi flees, taking refuge in Saudi Arabia.
In July, Aden becomes the de facto capital of the country and in October pro-government forces announce they have retaken control of the Bab al-Mandab strait, a key waterway for international shipping.
– Battle for aid port –
In June 2018, government fighters, backed by Saudi and Emirati ground forces, launch an offensive to retake the port of Hodeida.
UN-brokered talks between the warring parties open in December, yielding a series of breakthroughs including a ceasefire in Hodeida where combat largely ceases.
– Southern separatists –
The anti-Huthi camp is also divided, notably in the south with fighting between separatists and unionist forces loyal to the government. The separatists occupy the presidential palace, before Saudi-Emirati forces intervene and end the battle.
South Yemen was an independent state until it united with the north in 1990, and separatists remain powerful.
In August 2019, clashes in Aden pit separatists from the UAE-trained Security Belt against government troops backed by Riyadh.
In November, a power-sharing accord is signed between the two parties, but is never applied.
– Saudi Arabia targeted –
In September 2019, twin attacks on Saudi oil installations, claimed by the Huthis but widely blamed on Iran despite its denials, knock out half of the kingdom’s production.
Saudi Arabia has regularly been targeted by missiles and drones launched by the rebels.
– New escalation –
After a relative lull in violence, fighting resumes in mid-January 2020 to the east of Sanaa.
On January 18, a missile strike on a loyalist military camp blamed on the Huthis kills 116 people and injures dozens.
In early March, the Huthis seize key provincial capital Al-Hazm after heavy fighting with government troops.
The victory puts them on the road to Marin, a key city held by government forces situated 170 kilometres (105 miles) to the east of Sanaa.
– Humanitarian crisis –
Yemen’s conflict has killed tens of thousands of people, mostly civilians, relief agencies say.
More than 24 million Yemenis, or more than two thirds of the population, need assistance, according to the United Nations which describes Yemen as “the world’s worst humanitarian crisis”.
Both sides stand accused of committing violations that could amount to war crimes.