As the ruling party of Ethiopia's northern Tigray region fires rockets at the capital of neighbouring Eritrea, we look at the crisis stoking fears of a devastating conflict in Africa's second most populous country. Here is a timeline of the crisis:
Ethiopia's worrying clash with the ruling party of its northern region has roots in street protests that toppled the previous Tigray-dominated government in 2018.
While Tigrayans make up only 6 percent of Ethiopia's population, they dominate national politics for nearly three decades until the protests.
All that changes when Abiy Ahmed becomes premier in April 2018, the first ever from the Oromo ethnic group, the country's largest.
Tigrayans lose cabinet posts and some top military posts.
Oromos and Amharas -- Ethiopia's second biggest ethnic group -- as well as other groups felt marginalised under the old authoritarian coalition.
Ethnic violence and calls for greater autonomy erupt up in several parts of the country.
Abiy wins the Nobel Peace Prize in October 2019 for making peace with Eritrea, ending a bitter stalemate that dated back to a border war from 1998 to 2000.
But things are less peaceful at home.
Weeks after his Nobel win, the Tigray People's Liberation Front (TPLF) refuses to join Abiy's new ruling party, complaining they are 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 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, while Tigrayan leaders in turn no longer recognise 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 air strikes on Tigray with Abiy saying the operation will be all over "soon".
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 almost 25,000.
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.
The next day the UN calls for an inquiry into "war crimes" in the region.
That night Tigray fires "missiles" at two airports it claims are being used by the Ethiopian military in the neighbouring state of Amhara.
On Saturday, Tigray threatens missile attacks on Asmara, the capital of neighbouring Eritrea. It says Eritrea is helping the federal forces.
Later in the evening the area around Asmara's airport is hit by several rocket strikes, prompting fears of a regional conflict.
Tigray's president Debretsion Gebremichael claims reponsibility Sunday, saying Ethiopian fighters were using the airport.