Here is a timeline of the fighting, which had eased since a 2022 truce but now risks flaring up again in a wider Middle East conflagration which may be fuelled by the Israel-Hamas war:

- 2014: rebels take capital -

In July 2014, Huthi rebels from the Zaidi sect, an offshoot of Shiite Islam that complains of discrimination by the central government, advance from their stronghold in the northern mountains.

The Iran-backed Huthis ally themselves with forces loyal to ex-president Ali Abdullah Saleh, who was toppled in a 2011 uprising, and seize the capital Sanaa and, later, the Red Sea port of Hodeida.

- 2015: Saudi enters war -

A coalition led by Iran's bitter enemy Saudi Arabia and the United Arab Emirates enters the conflict in March with air strikes targeting the rebels.

President Abedrabbo Mansour Hadi flees first to the southern city of Aden, which the rebels try but fail to take, then to Saudi Arabia.

In October, the Saudi-led coalition forces take control of the Bab al-Mandeb Strait at the southern entrance to the Red Sea, one of the world's most strategic waterways.

- 2018: battle for key port -

In June, government fighters backed by coalition ground forces launch an offensive to retake Hodeida, a major entry point for humanitarian aid.

- 2019: Saudi oil hit -

In September, the Huthis carry out drone and missile attacks on Saudi oil fields, halving the kingdom's crude output.

- 2021: US outreach to Huthis -

In February, the US ends its support for the Saudi-led coalition's military operations and removes the Huthis from a "terrorist" list to try encourage the Huthis to enter peace talks.

- 2022: six-month truce -

In early 2022, the Huthis attack oil facilities in the United Arab Emirates and Saudi Arabia but momentum builds towards a truce.

A UN-brokered ceasefire starts on the first day of the Muslim holy month of Ramadan on April 2.

Renewed twice, it expires in October but largely holds.

- 2023: Saudi-Iran detente -

In a surprise Chinese-brokered move, Iran and Saudi Arabia agree in March to restore ties seven years after they were severed.

The rapprochement sparks hope for a lasting peace in Yemen, where the Huthis and the government agree a prisoner swap.

In September, the rebels take part in five days of talks with Saudi Arabia in Riyadh but fail to reach a breakthrough on ending the war.

- Red Sea ships under attack -

In November, the Huthis begin attacking vessels crossing the Red Sea and linked to Israel. They say the attacks are in retaliation for Israel's war against Hamas in Gaza after the Palestinian group stormed across the border on October 7 in an unprecedented attack which left 1,140 dead in southern Israel, according to an AFP tally based on official Israeli figures.

Relentless Israeli bombardment of Gaza since October has left more than 23,400 people dead.

On November 19, the rebels seize a vessel owned by an Israeli businessman and divert it to Hodeida.

Over the next two months they target numerous vessels passing through the Red Sea, a gateway to the Suez Canal -- the quickest shipping link between Europe and Asia.

In December, the US sets up an international naval coalition to defend against the attacks.

- January 2024: US, Uk strikes on Yemen -

On January 9, the Huthis launch a major barrage of drones and missiles towards international shipping lanes.

Britain says "enough is enough".

On January 12, US and British forces carry out air strikes on 60 targets at 16 Huthi locations in several rebel-held Yemeni cities, including an airbase, airports and a military camp.