Washington says as many as half a million people have died in the fighting, while Olusegun Obasanjo, the African Union's envoy to the region, has said it could be up to 600,000.

Here is a timeline:

- 2020: troops enter Tigray -

On November 4, Abiy launches military operations against the Tigray People's Liberation Front (TPLF), a former guerrilla group that dominated Ethiopian politics for nearly three decades before he took power, and which he accuses of attacking federal army bases.

Eritrea, which fought a war with the TPLF from 1998 to 2000, sends troops into Tigray to help Ethiopian forces.

Two weeks later, Tigray's capital Mekele falls to government forces.

- 2021: Tigrayans advance -

In June, the rebels retake Mekele and push into the neighbouring regions of Amhara and Afar.

Abiy is sworn in for a new five-year term on October 4. In November, he announces a state of emergency and goes to the frontline to personally direct his troops in battle.

A UN investigation warns of suspected crimes against humanity by all sides.

- 2022: humanitarian truce -

In March, the government and rebels agree to a truce to help accelerate the delivery of emergency aid to the region. The rebels accept a ceasefire.

In late August, the truce falls apart as fighting resumes on Tigray's southern border. The fighting hinders the transportation of UN humanitarian aid.

On September 1, rebels denounce a joint offensive by Ethiopian and Eritrean forces against the north of Tigray from Eritrea.

- Peace talks -

On October 5, the government and rebels both say they have accepted an invitation to peace talks in South Africa, but they do not take place.

UN Secretary General Antonio Guterres warns the situation "is spiralling out of control" as government forces take control of Shire and two other Tigrayan towns.

The talks begin on October 25 in the South African capital Pretoria.

On November 2, the warring sides agree to a "cessation of hostilities", and the African Union hails the deal as a new "dawn" for Ethiopia.

The TPLF agrees to disarm in return for the restoration of access to Tigray. Communications, banking and electricity are then slowly restored to the region and there has been some resumption of aid deliveries.

- 2023: off terror list -

On Wednesday, in a key step in the peace process, Ethiopia's parliament removes the TPLF from the official list of terrorist groups.

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