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Why are Ethiopia and Eritrea heading back to war?

Eritrea fought beside Ethiopia's army in the last Tigray war. Now the two governments trade accusations at the UN, have cut diplomatic ties, and drones are striking inside Tigray. The dispute reaches back to how Eritrea left Ethiopia, and to a landlocked country that wants a coast.

Published 29 Oct 2026 By Implica 9 sources 8 min read

THE SHORT ANSWER

Because two disputes have collided: Ethiopia's wish for access to the Red Sea and a renewed rebellion in Tigray that Addis Ababa says Eritrea backs. Ethiopia told the UN Security Council that Eritrean forces made an "all-out invasion", advancing up to 60km. Eritrea denies backing the rebels and says Ethiopia is pursuing an "unprovoked war of aggression" to seize its port of Assab. The two countries cut diplomatic ties in early October 2026. They have fought one border war before, from 1998 to 2000.

What happened

A rebel alliance launched an offensive against Ethiopia's government in September. It includes the Tigray People's Liberation Front, or TPLF, the party that runs Tigray, the northern region bordering Eritrea. Ethiopia's army pushed back and entered the regional capital, Mekelle, on 4 October. Witnesses told AFP that rebels also lost the Tigrayan cities of Shire and Adigrat. Ethiopia expelled diplomats from Eritrea and Egypt in early October, and Eritrea then cut diplomatic ties altogether.

On 8 October, Ethiopia's foreign minister, Gedion Timothewos, wrote to the UN Security Council. He said Eritrean troops had advanced up to 60km into Tigray and that Ethiopia had "no option but to defend itself". A foreign security source told AFP that 5,000 to 8,000 Eritrean soldiers were in Tigray. Eritrea's information minister, Yemane Gebremeskel, rejected the claim. He said Ethiopia had waged an unprovoked war for more than three years and accused it of using the crisis to take Assab. His statement did not address the reports of Eritrean troops. Ethiopian drones reportedly struck Eritrean forces in Adigrat on 7 and 8 October. There were no verified reports of casualties, and the BBC could not report from Tigray.

On 28 October, Prime Minister Abiy Ahmed announced in Moscow, at a Russia-Africa summit, that Ethiopia had received 12 Russian Su-35 fighter jets. He said they arrived a year early. He also said Ethiopia plans to buy four S-400 air defence systems, and gave no delivery date. He said the equipment would help "pre-emptively deter aggression". He did not name an enemy. Fighting continues in Tigray and in the neighbouring Amhara region.

Why it matters

Eritrea and Ethiopia fought a war from 1998 to 2000 in which an estimated 70,000 to 80,000 people died. The Tigray war of 2020 to 2022 killed hundreds of thousands. Both neighbours now have armies close to each other, no diplomatic channel, and a leader in Addis Ababa who has called sea access a priority. The Horn of Africa is also already tense, and Ethiopia's new jets add outside arms suppliers to the picture.

  • For Ethiopia, The government says it is defending its territory and wants to restore sea access through peace and dialogue. It is also fighting rebels in Tigray and Amhara at the same time.
  • For Eritrea, Asmara says it faces a war aimed at taking its territory and its port of Assab. It denies backing the TPLF.
  • For Tigray's people, Their region is again the battlefield, only a few years after a war that devastated its health system and displaced more than a million people at one point.
  • For neighbours and arms sellers, Russia gains a large customer. Our reading is that Egypt and Sudan, already at odds with Ethiopia over the Nile dam, may seek upgrades of their own.

The background: a coastline lost and a border never settled

Old ties and Italian rule

The lands of today's Ethiopia and Eritrea have been linked since ancient times. The Kingdom of Aksum, which lasted from the first century AD into the early Middle Ages, covered parts of both. Italy colonised Eritrea in 1882. In 1889 Emperor Menelik II recognised Italian rule over territory north of the Mereb River in the Treaty of Wuchale. Italian troops that tried to push into Ethiopia were defeated at the Battle of Adwa on 1 March 1896.

Italy invaded Ethiopia in October 1935, partly from Eritrea, and incorporated it into Italian East Africa in 1936. British troops conquered both territories during World War II, and Eritrea was run by a British military administration until 1951.

Federation and the war of independence

The United Nations General Assembly voted in December 1950 to federate Eritrea with Ethiopia. The federation was formed on 15 September 1952, with Eritrea as an autonomous part under the Ethiopian crown. Its autonomy was gradually eroded. Eritrean insurgents began fighting for independence on 1 September 1961. After Emperor Haile Selassie was overthrown in 1974, the Marxist Derg government kept up the war.

The Eritrean People's Liberation Front, led by Isaias Afwerki, came to dominate the rebellion. The TPLF helped it in its fight with a rival Eritrean group. In 1991 an Ethiopian coalition led by the TPLF overthrew the Derg, and Eritrean fighters took Asmara in May. An April 1993 referendum produced an almost unanimous vote for independence, and Eritrea became a sovereign state on 24 May 1993. Ethiopia accepted the result, but it lost its coastline. It kept using the Eritrean ports of Assab and Massawa for trade.

The border war

Relations were friendly at first, but quarrels over trade, currency and the exact border grew. Eritrea introduced its own currency in 1997. In May 1998, border incidents around the town of Badme became open war. Accounts differ on who started it. The fighting spread along the whole border and killed an estimated 70,000 to 80,000 people.

A peace agreement was reached in June 2000, and the Algiers Agreement was signed that December. UN peacekeepers watched a buffer zone. In April 2002 a boundary commission gave Badme to Eritrea. From 2000 to 2018 the two states stayed hostile, with no diplomatic ties and the border closed. Eritrea kept a large force on the border.

Peace in 2018, then a shared war

Abiy Ahmed became prime minister, and in July 2018 he and Isaias Afwerki pledged in Asmara to restore ties and open the border. A joint declaration ending the conflict followed the next day, and another agreement was signed in Jeddah in September. When the Tigray war began in November 2020, Eritrean troops fought alongside Ethiopia's army against the TPLF. The war ended in November 2022 with a peace deal between Ethiopia and the TPLF. Eritrea was not directly involved in those talks. Eritrea still occupied parts of Tigray as of late 2024.

Sea access and the new crisis

Eritrea says Ethiopia declared war on it in 2023 by stating that it would gain sovereign access to the sea. From 2024, tensions rose over regional security and Ethiopia's interest in Eritrean ports, including Assab. In February 2025 Eritrea banned Ethiopian Airlines flights to Asmara and mobilised its military. In June 2025 a section of the border at Zalambessa reopened, bringing Eritrean and Tigrayan communities together for the first time since the war.

In late January 2026 fighting broke out in Tigray between Tigrayan forces and federal troops backed by Amhara militias. In September a rebel alliance began its offensive. The October events followed: expulsions, severed ties, reports of Eritrean troops, and the exchange of letters and accusations.

GOOD TO KNOW

After Eritrea's independence in 1993, Ethiopia became the world's most populous landlocked country, with roughly 120 million people and no coastline of its own.

Why does Assab matter to Ethiopia?

Assab is an Eritrean Red Sea port. Ethiopia has had no coastline since 1993 and is now the world's most populous landlocked country. Addis Ababa calls restoring sea access an existential issue but has said it would be done through peace and dialogue. Eritrea points to statements by Ethiopian officials and says Ethiopia wants to take Assab by force. The reports so far do not show Ethiopia saying it will attack the port. Abiy did say at his swearing-in that access to the sea was a priority, and DW reported that this fed speculation about Assab.

Who is the TPLF, and where does Eritrea fit?

The Tigray People's Liberation Front led the coalition that ruled Ethiopia from 1991 and was once an ally of Eritrea's fighters. It then fought Eritrea in 1998 to 2000, and Eritrea fought it in 2020 to 2022. Tigrinya, a language of Tigray, is also spoken in Eritrea, and the peoples on both sides of the border are closely related. Ethiopia now says Eritrea is backing the TPLF, which has joined an alliance of seven armed groups. Eritrea denies it. The reports so far do not give evidence on either side of that claim.

Timeline: 1882 to today

COLONIAL RULE AND UNION

  1. Italy colonises Eritrea.

  2. In the Treaty of Wuchale, Menelik II recognises Italian rule north of the Mereb River.

  3. Menelik's army defeats Italian troops at the Battle of Adwa.

  4. Italy invades Ethiopia, partly from Eritrea.

  5. Eritrea is federated with Ethiopia under the Ethiopian crown.

INDEPENDENCE WAR

  1. Eritrean fighters begin a war for independence.

  2. The Derg falls and Eritrean fighters take Asmara.

  3. Eritrea becomes a sovereign state after a referendum, and Ethiopia loses its coastline.

BORDER WAR AND STANDOFF

  1. Eritrea introduces its own currency, sharpening economic disputes.

  2. Fighting around Badme starts a full-scale war.

  3. The sides agree to a comprehensive peace agreement and binding arbitration.

  4. A boundary commission awards Badme to Eritrea.

PEACE AND THE TIGRAY WAR

  1. Abiy Ahmed and Isaias Afwerki sign a joint declaration ending the border conflict.

  2. The Tigray war begins, with Eritrean troops fighting beside Ethiopia's army against the TPLF.

  3. The Tigray war ends with a peace deal between Ethiopia and the TPLF, which Eritrea was not directly part of.

RENEWED TENSION

  1. Ethiopia states it will gain sovereign access to the sea, which Eritrea later calls a declaration of war.

  2. Eritrea bans Ethiopian Airlines flights to Asmara and mobilises its military.

  3. Clashes erupt in Tigray between Tigrayan forces and federal troops backed by Amhara militias.

  4. Government forces enter Mekelle after a rebel offensive that began in September.

  5. Ethiopia tells the UN that Eritrea invaded, and Eritrea calls it an unprovoked war of aggression.

  6. Abiy announces in Moscow that Ethiopia has received 12 Russian Su-35 jets and plans to buy four S-400 systems.

What to watch next

  • The Security Council. Ethiopia has written to all council members asking for support, and the reports so far do not say how the council will respond.
  • Eritrean troops in Tigray. Ethiopia demands their withdrawal, and Eritrea's statements have not addressed the reports that they are there.
  • The S-400 systems. Abiy gave no delivery date, price or basing details for the air defence systems or the jets.
  • Fighting in Tigray and Amhara. Battles with rebels continue in both regions, and the outcome will affect how far the crisis with Eritrea spreads.

Sources

How this article was made: Implica's editorial system wrote it from the news reports above, with the background drawn from Wikipedia: Eritrean War of Independence, Eritrean–Ethiopian War, Tigray war, Eritrea–Ethiopia relations.

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