A full-scale war is already raging, according to one of the leaders of the Tigray People's Liberation Front (TPLF).
"We are in a full-scale war now," the group's deputy chairman, Amanuel Assefa, told AFP.
Artillery fire has been reported in parts of northern Ethiopia. TPLF-led rebel forces recently took control of Tigray's largest airport. Fighting is also reported to be continuing in the neighbouring Amhara and Afar regions.
Government forces said on Thursday that 272 rebels had been killed in Amhara.
The rebels describe it as a defensive war to overthrow an autocracy in Addis Ababa. The government describes it as a broad attack with coordinated offensives in several directions.
Former enemies
This time, the resistance has formed an alliance with militias from several of Ethiopia's diverse ethnic groups, many of which have previously occasionally fought each other, or for the government.
As in many previous conflicts, neighbouring Eritrea plays a role. During the civil war that raged between 2020 and 2022, Eritrean forces helped suppress the Tigrayan resistance on the national border.
Since then, the governments have been at odds. A major point of contention has been Ethiopia's interest in gaining access to an Eritrean port on the Red Sea - which has led Eritrea to fear a military attack. Eritrea is then considered to have instead started supporting rebels in Ethiopia.
Added to this is the huge war in neighbouring Sudan, where the countries have each chosen their own side.
The road to Addis
In recent months, there have been sporadic skirmishes and drone strikes in northern Ethiopia.
In the new offensive, rebel forces have so far entered the border areas of Tigray's neighbouring regions and taken control of communities in two directions.
Their stated goal is to take Addis, but it is not known what tactical manoeuvres they are planning to use to reach the city, Norwegian expert Kjetil Tronvoll told AFP.
In November 2020, the Ethiopian government launched a military offensive in the Tigray region in the north, against forces belonging to the Tigray People's Liberation Front (TPLF), which was then leading the region's self-rule.
The TPLF had accused Prime Minister Abiy Ahmed of ruling like a dictator and declared that the central government lacked legitimacy. The TPLF led the entire government of Ethiopia from 1991 to 2018. Abiy Ahmed, who took over, is from the Oromo ethnic group.
The Ethiopian army was supported by Eritrea, which attacked the TPLF from the north. Other ethnic militias in the country took sides. The fighting spread to the neighbouring Amhara and Afar regions. The warfare was characterised by massacres and sexual violence, with perpetrators on both sides, but independent observers had very limited insight.
Several hundred thousand civilians are estimated to have been killed in the conflict and up to a million are still estimated to be internally displaced. In November 2022, the parties signed a peace agreement that, in short, meant that the central government re-established control over Tigray.
