Venezue­lans are vot­ing in a ref­er­en­dum Sun­day to sup­pos­ed­ly de­cide the fu­ture of a large swath of neigh­bour­ing Guyana that their gov­ern­ment claims own­er­ship of, ar­gu­ing the ter­ri­to­ry was stolen when a north-south bor­der was drawn more than a cen­tu­ry ago.

Guyana con­sid­ers the ref­er­en­dum a step to­ward an­nex­a­tion, and the vote has its res­i­dents on edge. It asks Venezue­lans whether they sup­port es­tab­lish­ing a state in the dis­put­ed ter­ri­to­ry, known as Es­se­qui­bo, grant­i­ng cit­i­zen­ship to cur­rent and fu­ture area res­i­dents and re­ject­ing the ju­ris­dic­tion of the Unit­ed Na­tions’ top court in set­tling the dis­agree­ment be­tween the two South Amer­i­can coun­tries.

“We are solv­ing through con­sti­tu­tion­al, peace­ful and de­mo­c­ra­t­ic means an im­pe­r­i­al dis­pos­ses­sion of 150 years,” Pres­i­dent Nicolás Maduro said af­ter vot­ing in a mil­i­tary com­plex in Cara­cas, the cap­i­tal.

The In­ter­na­tion­al Court of Jus­tice on Fri­day or­dered Venezuela not to take any ac­tion that would al­ter Guyana’s con­trol over Es­se­qui­bo, but the judges did not specif­i­cal­ly ban of­fi­cials from car­ry­ing out Sun­day’s five-ques­tion ref­er­en­dum. Guyana had asked the court to or­der Venezuela to halt parts of the vote.

The le­gal and prac­ti­cal im­pli­ca­tions of the ref­er­en­dum re­main un­clear. But in com­ments ex­plain­ing Fri­day’s ver­dict, in­ter­na­tion­al court pres­i­dent Joan E. Donoghue said state­ments from Venezuela’s gov­ern­ment sug­gest it “is tak­ing steps with a view to­ward ac­quir­ing con­trol over and ad­min­is­ter­ing the ter­ri­to­ry in dis­pute.”

“Fur­ther­more, Venezue­lan mil­i­tary of­fi­cials an­nounced that Venezuela is tak­ing con­crete mea­sures to build an airstrip to serve as a ‘lo­gis­ti­cal sup­port point for the in­te­gral de­vel­op­ment of the Es­se­qui­bo,’” she said.

The 61,600-square-mile (159,500-square-kilo­me­ter) ter­ri­to­ry ac­counts for two-thirds of Guyana and al­so bor­ders Brazil, whose De­fense Min­istry ear­li­er this week in a state­ment said it has “in­ten­si­fied its de­fense ac­tions” and boost­ed its mil­i­tary pres­ence in the re­gion as a re­sult of the dis­pute.

Es­se­qui­bo is larg­er than Greece and rich in min­er­als. It al­so gives ac­cess to an area of the At­lantic where oil in com­mer­cial quan­ti­ties was dis­cov­ered in 2015, draw­ing the at­ten­tion of Maduro’s gov­ern­ment.

Venezuela’s gov­ern­ment pro­mot­ed the ref­er­en­dum for weeks, fram­ing par­tic­i­pa­tion as an act of pa­tri­o­tism, and of­ten con­flat­ing it with a show of sup­port for Maduro. His gov­ern­ment held a mock ref­er­en­dum last month, but it did not re­lease par­tic­i­pa­tion fig­ures or re­sults.

Venezuela has al­ways con­sid­ered Es­se­qui­bo as its own be­cause the re­gion was with­in its bound­aries dur­ing the Span­ish colo­nial pe­ri­od, and it has long dis­put­ed the bor­der de­cid­ed by in­ter­na­tion­al ar­bi­tra­tors in 1899 when Guyana was still a British colony.

That bound­ary was de­cid­ed by ar­bi­tra­tors from Britain, Rus­sia and the Unit­ed States. The U.S. rep­re­sent­ed Venezuela on the pan­el in part be­cause the Venezue­lan gov­ern­ment had bro­ken off diplo­mat­ic re­la­tions with Britain.

Venezue­lan of­fi­cials con­tend that Amer­i­cans and Eu­ro­peans con­spired to cheat their coun­try out of the land and ar­gue that a 1966 agree­ment to re­solve the dis­pute ef­fec­tive­ly nul­li­fied the orig­i­nal ar­bi­tra­tion.

Guyana, the on­ly Eng­lish-speak­ing coun­try in South Amer­i­ca, main­tains the ini­tial ac­cord is le­gal and bind­ing and asked the In­ter­na­tion­al Court of Jus­tice in 2018 to rule it as such, but a rul­ing is years away.

Vot­ers on Sun­day will have to an­swer whether they “agree to re­ject by all means, in ac­cor­dance with the law,” the 1899 bound­ary and whether they sup­port the 1966 agree­ment “as the on­ly valid le­gal in­stru­ment” to reach a so­lu­tion.

Maduro and his al­lies are urg­ing vot­ers to an­swer “yes” to all five ques­tions in the ref­er­en­dum.

Venezue­lans hold as self-ev­i­dent truth that their home­land’s east­ern end in­cludes the Es­se­qui­bo re­gion. They learn about the ter­ri­to­r­i­al dis­pute from a young age, with text­books in­clud­ing the his­tor­i­cal back­ground and maps mark­ing the ter­ri­to­ry with di­ag­o­nal lines.

Ad­min­is­tra­tive as­sis­tant Henghel Niño, 45, re­mem­bers those lessons. Out­side a vot­ing cen­tre in Cara­cas, she said she par­tic­i­pat­ed in the ref­er­en­dum be­cause Venezue­lans “must de­fend our Es­se­qui­bo.” But like many oth­er vot­ers, she was not clear about the ac­tions that could re­sult from the ref­er­en­dum’s re­sults.

“I imag­ine that (the Guyanese) must be wor­ried about the con­se­quences that this sit­u­a­tion may bring, but hey, we have to try to re­cov­er our lands be­cause there are many min­er­als there,” Niño said, adding that she be­lieved Venezuela’s gov­ern­ment or­ga­nized the ref­er­en­dum “to try to re­cov­er (Es­se­qui­bo) legal­ly” in a ne­go­ti­a­tion with Guyana.

“I imag­ine that the use of weapons would be the last al­ter­na­tive,” she said.

Guyana Pres­i­dent Mo­hamed Ir­faan Ali on Sun­day ac­knowl­edged the ap­pre­hen­sion many Guyanese have over the ref­er­en­dum and sought to re­as­sure them, telling them they have “noth­ing to fear over the next num­ber of hours, days, months ahead.” He said Guyana is us­ing diplo­ma­cy as its “first line of de­fense” and is work­ing con­tin­u­ous­ly to en­sure its bor­ders “re­main in­tact.”

“I am not go­ing to get in­to the in­ter­nal pol­i­tics of Venezuela and in­to their pol­i­cy-mak­ing, but I want to ad­vise Venezuela that this is an op­por­tu­ni­ty for them to show ma­tu­ri­ty, an op­por­tu­ni­ty for them to show re­spon­si­bil­i­ty, and we call up­on them once more join us in ... al­low­ing the rule of law to work and to de­ter­mine the out­come of this con­tro­ver­sy,” Ali said.

Gar­cia Cano re­port­ed from Mex­i­co City. As­so­ci­at­ed Press pho­tog­ra­ph­er Ma­tias Delacroix con­tributed to this re­port.

CARA­CAS, Venezuela (AP) —