As Ethiopian Prime Minister Abiy Ahmed orders a "final" offensive on the dissident leaders of the northern Tigray region, we look at the worrying conflict in Africa's second most populous country.
A timeline of the crisis:
The fighting has its roots in street protests that toppled the previous Tigray-dominated government in 2018.
While Tigrayans make up only six percent of Ethiopia's population, they dominate national politics -- and the military -- for nearly three decades after leading the revolt against autocrat Mengistu Hailemariam in 1991.
All that changes when Abiy Ahmed becomes prime minister in April 2018, the first ever from the Oromo ethnic group, the country's largest.
Oromos and Amharas -- Ethiopia's second biggest ethnic group -- felt marginalised under the old authoritarian coalition.
Abiy wins the Nobel Peace Prize in October 2019 for initiating a rapprochement with Eritrea, ending a stalemate that dated back to a border war that lasted from 1998 to 2000.
Weeks after his Nobel win, the Tigray People's Liberation Front (TPLF) refuses to join Abiy's new ruling party, complaining it is being sidelined and unfairly targeted by corruption probes.
TPLF leaders return to their region, with Abiy accusing them of trying to destabilise the country.
Elections set for August 2020 are postponed due to the coronavirus pandemic despite opposition protests, and no new date is set.
Tigray defies Abiy by going ahead with its own elections on September 9. Addis Ababa brands the Tigray government unlawful, which in turn says it no longer recognises Abiy's administration.
Federal funds to the region are slashed, which the TPLF says is "tantamount to an act of war".
On November 4, Abiy orders a military response to a deadly "traitorous" attack on federal army camps in Tigray. The TPLF denies responsibility and says the reported attack is a pretext for an "invasion".
Two days later, with fighting intensifying, Abiy sacks the head of the military, whose top brass contains many battle-hardened Tigrayans.
On November 9, Ethiopia carries out more air strikes in Tigray with Abiy saying the operation will be all over "soon".
Refugees and 'war crimes'
Thousands of refugees flee into neighbouring Sudan as the African Union follows the UN in demanding an end to the fighting.
Refugee flows later swell to 40,000.
On November 12, Amnesty International says many civilians have been killed in a massacre which witnesses say was carried out by forces loyal to the Tigray government. The TPLF denies involvement.
That night Tigray fires "missiles" at two airports it claims are being used by the Ethiopian military in the neighbouring state of Amhara.
On November 14, Tigray threatens missile attacks on Asmara, the capital of neighbouring Eritrea. It says Eritrea is helping the federal forces.
After three weeks of fighting in which he rejected peace talks, Abiy says government tanks are advancing on Tigray's capital, Mekele.
On Thursday he orders the "final phase" of the attack with the army saying it is encircling the city and its half a million inhabitants.
