An arbitration commission at The Hague has ruled that Eritrea violated international law when it invaded northern Ethiopia in May 1998.
The ruling from the Eritrea-Ethiopia Claims Commission said the attack could not be justified as lawful self-defense under the United Nations charter.
But the commission also said Ethiopia broke international law during the two countries' border conflict between 1998 and 2000 that killed some 70,000 people.
Since the signing of a peace treaty in 2000, the two nations have allowed U.N. peacekeepers along their shared border to help prepare for a formal demarcation.
But after Ethiopia rejected the border drawn by an international boundary commission, Eritrea asked some U.N. peacekeepers to leave. The developments have sparked worries that another armed conflict over the border could occur.
Some information for this report provided by AFP and Reuters.