In 1998, the Eritrean–Ethiopian War broke out. Though border disputes and politico-economic tensions were the immediate the causes, denationalizations by both countries fueled the conflict. On 12 June 1998, large-scale deportations of Eritreans from Ethiopia began. Many of the deportees identified as Ethiopian and the rules were arbitrary. Some deportations were based on people for whom both parents were originally Eritrean, some were of children from mixed parentage, still others targeted only those with Eritrean fathers, or only those with Eritrean mothers. Ethiopia began using the rolls of voters who took part in the referendum as a basis to denationalize and expel Eritreans, but many were deported who had not taken part. Eritreans interned and deported Ethiopians residing in their territory later in the conflict. The war ended officially on 12 December 2000 when the Algiers Agreement was signed.