Why does Guatemala claim half of Belize?

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This is the script for my video posted on October 5, 2026. Watch it on TikTok.

Guatemala claims about half the land in neighboring Belize, plus all of its islands, in one of the few live territorial disputes in Latin America today. The International Court of Justice is scheduled to hear oral arguments on the case in February 2027, the last stage before a ruling that could result in dramatic border changes. But why does Guatemala claim so much of Belize to begin with, and how does it shape the region's geopolitics?

The story begins in 1494 when Portugal and Spain signed the Treaty of Tordesillas, which basically split the world between the two countries to prevent them from competing for territory.

Spain claimed exclusive rights to all newly discovered lands west of a meridian 370 leagues west of the Cape Verde islands, giving Portugal the right to what’s now eastern Brazil while Spain claimed most of the Americas, including what is now Central America.

But in the 17th century, buccaneer merchants from England and other countries, later known as Baymen, started to harvest logwood, a valuable source of dye, along that coast without Spanish permission. Spain expelled them four separate times between 1717 and 1780, but they kept coming back.

Under the 1763 Treaty of Paris, Britain finally got the right to cut and export logwood, but they had to demolish their forts, and Spain kept sovereignty over the land. That gap between using the land and owning it sits at the root of the entire dispute.

In the following decades, the sides continued to negotiate, and under the 1786 Convention of London, British logging rights expanded south to the Sibun River, the same line Guatemala's claim follows today. To get the larger area, Britain evacuated the Mosquito Coast of modern Nicaragua and Honduras. Britain was still barred from having fortifications, a government presence, or plantations, and Spain could make inspections twice per year.

But when Spain and Britain went to war in the 1790s, Spain saw a chance to expel the British settlers and regain full control of the region. In 1798, the Spanish governor of Yucatan sent a fleet of about 30 vessels to remove them permanently, but it failed. At St. George's Caye, the Spanish were turned back by the Baymen, the enslaved men who fought alongside them, and a single Royal Navy sloop. Belize still celebrates that victory every September 10, but the battle did not change the legal picture because Spain never signed the land over.

In 1821, the Mexican War of Independence resulted in Mexico splitting from Spain, and the Spanish Captaincy General of Guatemala, which governed modern Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, and Chiapas, was cut off from royal support.

Local elites pushed to draft formal independence documents to prevent widespread upheaval or violent rebellion from below, and each eventually became its own country when the Federal Republic of Central America dissolved.

But Guatemala felt it had inherited Spain's claim to Belize, and in the tumult the Baymen expanded far south and west beyond the treaty limits, all the way to the Sarstoon River.

Under the Clayton-Bulwer Treaty of 1850, Britain and the US agreed not to occupy, fortify, or colonize any part of Central America. Britain had run Belize through a Crown-appointed superintendent for decades, but it had never been granted sovereignty there, so the prospect of making Belize a formal colony risked violating the treaty.

By the 1850s, Guatemala wanted a direct trade route from its capital to the Atlantic, and Britain wanted formal control over Belize. The result was the 1859 Wyke-Aycinena Treaty, which set Belize's modern western and southern border, running up the middle of the Sarstoon River, then overland and north to the Mexican border. The treaty describes that line as the boundary that already existed before Clayton-Bulwer, and Belize reads this as recognition of an existing border, while Guatemala argues it was a land transfer disguised as a boundary treaty to get around Clayton-Bulwer.

Britain formally declared the colony of British Honduras anyway in 1862. In 1863 Britain offered up to 50k pounds toward the route from Guatemala City to the coast that it had agreed to support. But Guatemala never ratified that deal, the road was never built, and Guatemala protested. In 1931, the two countries agreed to boundary monuments along part of the 1859 line, which Guatemala later claimed was not a recognition of the border.

In 1945, Guatemala declared in its new constitution that Belize was Guatemalan territory, and it soon declared the 1859 treaty void. Then in 1948 they threatened to invade and annex the territory, prompting Britain to deploy warships and ground troops. Guatemala proposed that the US mediate, while Britain offered the International Court of Justice, or ICJ, instead.

But in 1964, amid Britain's broader move away from colonialism, British Honduras gained the right to self-government. In 1968, a US mediator published proposals that critics said would have made Belize a Guatemalan satellite, giving Guatemala a share of control over its defense, foreign policy, and economy. This provoked riots in Belize City, and ultimately all parties rejected the plan.

Belizean nationalism had been growing since the 1950s, and in the late 1970s Belize won UN backing for independence with its territory intact. Guatemala kept threatening to invade, and Britain answered with Harrier jump jet deployments in 1975 and 1977. Belize finally became independent in 1981, with about 1500 British troops staying behind as a deterrent.

In 1985, Guatemala created a new constitution that replaced the claim over Belize with an article that authorizes the executive to resolve the rights of Guatemala with respect to Belize, and requires any definitive agreement to go to a popular referendum.

It took decades of negotiation for both sides to agree to take the issue to the ICJ. But it's still very much a live problem. On 10 September 2026, the anniversary of the 1798 battle, a flotilla of Guatemalan military and civilian boats blocked Belizean volunteers from their yearly trip around Sarstoon Island, at the mouth of the river that the 1859 treaty turned into the southern border. Two weeks later, Belize accused a Guatemalan military plane of entering its airspace, which Guatemala denies.

Today, according to a former Guatemalan vice foreign minister, Guatemala's claim covers all the land south of the Sibun River, roughly half of Belize's land, plus every island and the waters around them. Guatemala argues that it inherited Spain's title in 1821, that Britain held only logging rights north of the Sibun, and that the 1859 Wyke-Aycinena boundary treaty is void because Britain never delivered the road it promised.

Belize meanwhile, as the inheritor of Britain's claim, says that the 1859 treaty is a valid boundary treaty, that Spain never actually occupied the territory while Britain and then Belize have held it for more than two centuries, and that Guatemala itself recognized Belize as an independent nation in 1991, even while keeping its claim.

The practical impact on geopolitics is that Britain, which had the burden of defending Belize from 1948 to 1994 and kept the state viable, has a vested interest in supporting it. Today it provides no defense guarantee, but British troops still train in Belize's jungles under a 2019 defense cooperation treaty.

The Organization of American States, or OAS, has also been a key player in managing the territorial dispute. Starting in 2000, it helped set up a framework for peace that included an OAS office to verify incidents and a one-kilometer zone on either side of the dividing line, which the two sides call the Adjacency Line because Guatemala does not recognize it as a border. The OAS will be crucial on the ground while the case plays out, and in carrying out whatever the court decides.

The biggest practical stakes may be at sea. Guatemala's Caribbean coastline is short and boxed in by Belizean and Honduran waters, so its claim to every Belizean island could reshape its access to the open Caribbean and put much of the barrier reef in play. Honduras is involved too. It claims the Sapodilla Cayes at the southern tip of the reef, and the court will hear Belize's case against Honduras over them, with Guatemala joining, right after the February hearings.

But despite their disputes, Guatemala and Belize have a lot of commonality. In 2025, they announced plans with Mexico for a joint tri-national nature reserve. They are also the only two countries in Central America that still recognize Taiwan. And due to the porous western border and adjacency zone, the countries have a mutual interest in cooperating to mitigate trafficking of timber, cattle, and wildlife.

The hope is that Belize and Guatemala will fully accept whatever judgment the ICJ reaches and set aside their differences to move forward as neighbors. The ruling will be final and binding, but the court has no way to enforce it, and the decision will likely come months after the hearings finish. We'll just have to see how it plays out.

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