Guatemala has deployed 3,000 troops along its disputed border with Belize over a shooting that killed a Guatemalan teen, the countrys Defence Minister Williams Mansilla said on Friday.
Guatemala has made claims over more than half of Belize's territory dating back 150 years to when its small neighbour was a British colony known as British Honduras.
Mansilla said "It is a preventive measure, it is not a declaration of war," referring to the deployment.
Tension between the two Latin American countries have been rising despite an agreement which aims to resolve the territorial dispute in the International Court of Justice (ICJ).
After the shooting, both countries claimed that the incident happened on its side of the border.
According to Guatemala, Belizean soldiers shot and killed a 13-year-old Guatemalan boy who was walking home from field labour, and wounded his father and brother.
But Belize rejected this claim and defended itself by saying that one of its patrols was fired upon by Guatemalan civilians and it responded in "justifiable self-defence."
Belize's Prime Minister Dean Barrow, said he had met with Guatemalan President Jimmy Morales on the sidelines of a United Nations summit in New York to express concerns that Guatemalan measures "escalate tension to an utterly unacceptable degree."
Barrow said both sides agreed "there is an immediate need to de-escalate tensions."
Both countries have accused each other for the violence against their forces and citizens at the border area within the past two decades.
Escalated border dispute is the first foreign policy challenge for Morales, a former TV comedian who became Guatemala’s president after a suprise victory in the presidential election which was held in January.
Addressing the nation on Thursday, Morales accused Belize of "cowardice" over the shooting and emphasised that Guatemalan forces would maintain "strict protection for the sovereignty" of the shared border river.