The International Court of Justice (ICJ) ruled on Monday that the islands of Mbanie, Conga and Cocoteros off the coast of Gabon legally belong to Equatorial Guinea, settling a decadeslong dispute between the West African neighbors.

The three tiny islands, which are effectively uninhabited but are located in potentially oil and gas-rich waters, have been controlled by Gabon since its troops forcibly evicted Equatorial Guinean soldiers from Mbanie in 1972.

What was Gabon's claim?

In 2003, Gabon argued that a hitherto unknown treaty from 1974 known as the Bata Convention confirmed its sovereignty over the territories.

The honorary president of Gabon's Constitutional Court, Marie-Madeleine Mborantsuo, claimed that the Bata Convention "resolves all sovereignty issues regarding the islands and border delimitation."

What was Equatorial Guinea's claim?

But Equatorial Guinea has always rejected the argument, demanding an original copy of the treaty which Gabon has been unable to produce.

"No one had seen or heard of this supposed convention," the vice-minister of mines and hydrocarbons, Domingo Mba Esono, told ICJ judges in The Hague.

"Moreover, the document presented was not an original but was only an unauthenticated photocopy," he added.

Philippe Sands, a lawyer representing Equatorial Guinea, dismissed the Bata Convention as "scraps of paper," telling the world court: "You are being asked to rule that a state can rely on a photocopy of a photocopy of a purported document, the original of which cannot be found and of which no mention was made or any reliance placed for three decades."

What did the ICJ rule?

And, on Monday, the court agreed, ruling that the Bata Convention could not be seen as a treaty with force of law.

Instead, it ordered Gabon to acknowledge a treaty signed in Paris in 1900 dividing up French and Spanish colonial assets in the region which handed the islands to Spain, with sovereignty passing to Equatorial Guinea upon its independence from Madrid in 1968.

"The title that has force of law in so far as it concerns sovereignty over the islands ... is the title held by the Kingdom of Spain [until] October 12, 1968, to which the Republic of Equatorial Guinea succeeded," the court concluded.

"Sadly, neither of the two parties can find the original document," said Gabon's Mborantsuo, referring to the Bata Convention. "Archives were badly managed because of a number of things; unfavorable climate, a lack of trained personnel and lack of technology."

As a result of the dispute, which has been conducted amicably and diplomatically between the two neighbors, Gabonese troops will have to leave their base on Mbanie — which is barely one kilometer (about 0.6 miles) long.