In 1985, tensions rose between the Burkinabé and Malian governments as Sankara called for a revolution in Mali while Traoré's regime struggled to manage social unrest.

Overwhelmed by Mali's superior firepower, Burkinabé forces lost control of the Agacher border communities and resorted to guerrilla tactics to stall Malian tanks.

A ceasefire was reached on 30 December, and in early 1986 successful mediation by West African countries resulted in an agreement between Sankara and Traoré to avoid further hostilities.

The relatively poor performance of Burkina Faso during the war damaged the credibility of its revolutionary rulers and led them to project a more moderate international image.

In north-eastern Upper Volta, an approximately 160-kilometre-long (100 mi) portion of land bordered to the north by Mali and Niger to the east and centered around the Béli River was subject to a territorial dispute.

In response, the Organization of African Unity (OAU) created a mediation commission to resolve the disagreement and provide for an independent, neutral demarcation of the border.

Sankara became president, and the officers established the Conseil National de la Revolution (CNR) to rule the country in a left-leaning, revolutionary fashion.

With Algerian mediation, the two agreed to have the border dispute settled by the International Court of Justice (ICJ) and subsequently petitioned the body to resolve the issue.

[11] At the same time, a new joint commission for bilateral cooperation was established, and the following month, Upper Volta lifted its veto to allow Mali to join the West African Economic and Monetary Union as a conciliatory measure.

[12] Low rainfall in Mali created a severe drought in 1984, forcing Malian ranchers to drive their cattle south into northern Burkina Faso in search of water and adequate grazing land.

[2] In July 1985, Burkina Faso declared the Malian secretary general of the Economic Community of West Africa, Drissa Keita, a persona non grata after he criticised Sankara's regime.

[2][13][14] Around the same time Sankara and other key figures in the CNR became convinced that Traoré was harbouring opposition to the Burkinabé regime in Bamako and plotting to provoke a border war which would be used to support a counterrevolution.

Malian police crossed the boundary to arrest the murderer and also detained several members of a local Committee for the Defense of the Revolution who were preparing a tribunal.

Mali accused the military authorities of pressuring Malian citizens in the border villages of Dionouga, Sebba, Kounia, and Douna to register with the census, a charge which Burkina Faso disputed.

[2] The Malian government accused Burkina Faso of harassing local customary chiefs and forcing its nationals to accept Burkinabé identity cards.

[21] According to an analyses by the United States Central Intelligence Agency, it was also hoped that a war would distract the Malian populace from their country's troubled economy.

[22] Former Sankara aide Paul Michaud wrote that the Burkinabé president had actually intended to provoke Mali into conflict with the aim of mobilising popular support for his regime.

[3] Burkina Faso deployed the National Police to reinforce the army,[24] which was also joined by some armed Committees for the Defense of the Revolution and militia units.

[9] Mali mitigated Burkinabé counterattacks by conducting sorties with its MiG-21s, and Burkina Faso attempted to counter them by launching its sole MiG-17, though no air-to-air engagements occurred.

[11] Burkina Faso accused Mali of conducting its offensive with the aid of an unnamed imperialist power and said that the conflict was "no longer a question of territorial claim but a direct open war between forces of reaction and revolution, between retrogression and the progressive Burkinabé Government.

The Democratic Union of the Malian People, the state party of Mali, claimed the attacks inflicted significant damage and loss of life.

The tank had been abandoned in Burkina Faso after being damaged in a firefight during the initial invasion and was left behind after the Chief of the General Staff Bougary Sangaré prohibited a recovery mission while negotiations were ongoing.

As a result of the tank incident, it was decided at the meeting to demote Sangaré[21] from general to the rank of colonel and forcibly retire him,[20] and discharge two lower officers from the army.

[31] At a rally held after the war, Sankara conceded that his country's military was not adequately armed and announced the commutation of sentences for numerous political prisoners.

Despite the appeals for national unity during the war, in his New Year's message broadcast over Radio Mali, Traoré declared that there was a fifth column in the country and that Malian teachers had connections with Sankara.

[23] Following the ceasefire Burkina Faso and Mali both petitioned the ICJ to impose interim measures to prevent further conflict until the court delivered its decision.

Burkina Faso claimed that it had been the victim of Malian aggression, while Mali argued that it acted in self-defence by responding to Burkinabé occupation of its territory.

[38] The court responded by advising both parties to continue mediation under ANAD's auspices, work out a troop withdrawal agreement, and take all measures to avoid conflict pending the adjudication of the border dispute.

[39] The parties began their oral arguments before the ICJ in June,[40] and the court issued a ruling on the matter by a five-member panel of judges on 22 December 1986.

[41] The court split the disputed territory among the parties; Mali received the more-densely populated western portion and Burkina Faso the eastern section centered on the Béli.