On Thursday, judges with the International Court of Justice (ICJ), a branch of the United Nations, determined that the court has jurisdiction to settle a longstanding territorial dispute between Colombia and Nicaragua.

Following the decision, Colombian President Juan Manuel Santos announced that the country would no longer participate in court proceedings related to the case and asserted that Colombia would protect national territory “down to the last centimeter.”

At issue are Caribbean waters that extend from Nicaragua past the island of San Andrés, which is Colombian territory.

Nicaragua asked the court to determine whether it should own the rights to a continental shelf extending some 200 nautical miles into the Caribbean Sea, well past San Andrés.

The Colombian government has argued that those waters are critical to the San Andrés economy,  fishing in territorial waters and tourism, a key source of revenue for the archipelago.

The court was also asked to decide whether Colombia had violated Nicaraguan territorial sovereignty as laid out in a 2012 ICJ ruling establishing expanded maritime boundaries for the Central American country. President Santos refused to accept that ruling “until the rights of Colombians are guaranteed.”

Colombia formally withdrew from ICJ jurisdiction in November 2014 by pulling out of the Bogotá Pact, a 1948 treaty between 21 Western Hemisphere countries establishing appropriate channels for territorial disputes, among other things.

However, the court determined on Thursday that Colombia could not retroactively free itself from the obligations of that treaty.

Thursday’s decision doesn’t rule on Nicaragua’s demands, but is likely to extend an already lengthy legal battle between Colombia and Nicaragua.

The two countries have squabbled over territorial waters for well over 150 years, although perhaps the most critical period was in 1928, when Colombia and Nicaragua signed the Esguerra-Bárcenas Treaty.

That treaty recognized Colombian sovereignty over San Andrés and its surrounding archipelago, as well as over the island Providencia. An addition to the treaty in 1930 set up the 82nd meridian as the maritime boundary, but that line was modified in 2012 to give Nicaragua additional waters.

This is a developing story. Check back for more updates.