The Eritrean–Ethiopian border conflict was a violent standoff between Eritrea and Ethiopia as part of the violence in the Horn of Africa. This included sporadic clashes of their militaries, some of which took part in the larger Second Afar Insurgency. The border conflict had been ongoing since the Eritrean–Ethiopian War of 1998–2000, and included multiple clashes with numerous casualties, such as the 2016 Tserona clashes. Ethiopia eventually stated in 2018 that it would cede Badme to Eritrea, which effectively ended the twenty-year conflict. The two countries formally ended the conflict at the 2018 Eritrea–Ethiopia summit on 9 July 2018, by signing a joint agreement to resume peaceful diplomatic relations.
Eritrea achieved independence from Ethiopia in 1993, following a long armed struggle. The two countries fought again between 1998 and 2000 over the disputed territory of Badme, costing an estimated 70,000 to 80,000 lives.
On 8 May 1998, sporadic clashes over the border between Ethiopia and Eritrea which killed several Eritrean officials near the former disputed town Badme. A great force of Eritrean mechanised entered the former disputed town, as result there was a firefight between the Eritrean soldiers and the Tigrayan militia and security police they encountered. On 13 May 1998, 5 days after the incidents the Eritrean radio which described the incidents as a "total war" policy from Ethopia, also claimed that the Ethopian Army was mobilising for a full assault against Eritrea. The organisation Claims Commission found that this was in essence an affirmation of the existence of a state of war between belligerents, not a declaration of war, and that Ethiopia also notified the United Nations Security Council, as required under Article 51 of the UN Charter.
After the ceasefire was launched on 18 June 2000, both parties agreed to have a 25 kilometres (16 mi) wide Temporary Security Zone (TSZ). Within Eritrea, patrolled by the United Nations Mission in Ethiopia and Eritrea (UNMEE) an organisation for the border stabilising for future conflicts between the countries. On 31 July 2000, UNMEE was official launched and started patrolling the border. Half later on 12 December, a peace agreement was signed in Algiers, Algeria by both countries.
Conflict deepened in 2012, when Ethiopia launched an offensive into Eritrean-held territory. Three camps were attacked, and a number of people were killed or captured in the process. Several weeks prior to the offensive, Ethiopia blamed Eritrea for supporting the Ethiopian rebels, who staged a January 2012 raid in the northern Afar Region that killed five Western tourists. In June 2016, Eritrea claimed 200 Ethiopian soldiers were killed and 300 wounded in a Battle at Tsorona. On 10 October 2016, the Ethiopian Government claimed that Eritrea and Egypt were behind the Oromo protests.
On 8 July 2018, the Ethiopian Prime Minister Abiy Ahmed arrived in Asmara, Eritrea. Where his counterpart President Isaias Afwerki greeted him at Asmara International Airport, the day after both leaders signed a five-point Joint Declaration of Peace and Friendship declaring that "the state of war between Ethiopia and Eritrea has come to an end; a new era of peace and friendship has been opened."
After the Eritrea–Ethiopia peace summit in July, the Ethiopian Prime Minister Abiy requested to United Nations Secretary-General António Guterres to lift the United Nations' sanctions on Eritrea imposed largely due to the efforts of Ethiopian diplomacy—on Eritrea. The airpline company Ethiopian Airlines announced that it would resume flights to Asmara on Monday 16 July 2018.
Later in July, between 14–16 July President Isaias visited Ethiopia and its President Mulatu Teshome. Isaias affirmed the unity of Eritrea and Ethiopia, saying "henceforth, anyone who says Eritreans and Ethiopians are two different peoples is one that doesn't know the truth." He visited an industrial park in Awasa and presided over the reopening of the Eritrean Embassy. On 6 September, an Ethiopian embassy was reopened in the Eritrean capital Asmara. On 11 September for the first time in 20 years the Eritrea–Ethiopia border crossing was reopend. Five days later, both leaders signed an official new peace agreement in Jeddah, Saudi Arabia.