In 1989 Panama declared itself to be in a state of war with the United States. On 13 May 1998, at the outbreak of the Ethiopian-Eritrean War, Ethiopia, in what Eritrean radio described as a "total war" policy, mobilized its forces for a full assault against Eritrea. The 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.
In September 2005 the government of Chad declared that a state of war existed with Sudan, after Sudan hosted Chadian rebel groups that were behind fatal cross border raids.
In 2006, after armed clashes broke out during the Djiboutian–Eritrean border conflict, Djibouti's President Guelleh, when asked if his country was at war with Eritrea, replied with "absolutely".
On 11 April 2012, Sudan declared war on South Sudan after weeks of border clashes.