Out on Chile’s northernmost coastline, crews are turning the ground itself into an enforcement tool. On a wide plain near Arica, military excavators dig trenches along concrete markers that trace the border with Peru, while Peruvian border police sit across the pampa watching warily.
The work is part of “Border Shield,” a border-control program promoted by new far-right President José Antonio Kast as a direct response to the migration crisis that helped propel him to power in December’s runoff, when he won 58% of the vote. The project has also been repeatedly linked to Donald Trump’s immigration agenda, including Trump’s pledges to build a wall along the U.S.–Mexico border.
Kast’s backing for stronger border controls includes rhetoric from the campaign and early in his presidency, when he visited the frontier and said: “We want to use excavators to build a sovereign Chile… which has been undermined by illegal immigration, drug trafficking, and organized crime.” The emphasis in his messaging is tied to a broader platform that has focused on illegal immigration and the public-security fears officials associate with it, including by describing himself in ways that have drawn comparisons to Trump.
In Chile’s northernmost administrative region, Cristián Sayes, President Kast’s delegate for the program, said officials are tracking progress in physical terms. “We have made 53.6% progress, which means about six kilometres in this area,” Sayes said. He also described the “ultimate goal” as constant control of the border to stop illegal migration “once and for all,” while also confronting drug trafficking, smuggling, and human trafficking.
According to Sayes, the initial engineering effort relies on multiple trench lines rather than a single continuous barrier. He said a ditch would be 11 kilometers long in one stretch, with another in the mountains reaching seven kilometers, and that additional ditches are planned further south along the border with Bolivia. The landscape is already marked by older defenses and hazards, including tank traps from political tensions in the 1970s and desert sections that still have anti-tank mines from that era.
He said the program’s first phase focuses on short trench sections in the most exposed parts of Chile’s roughly 1,200-kilometer border shared with Peru and Bolivia across the three northernmost regions in the Atacama Desert. Surveillance equipment, he said, would come in a next phase, following the trenching; Sayes described thermal and infrared cameras, sensors, radars, and drones with facial-recognition cameras that would operate 24 hours a day.
At the same time, Chile’s security agencies say the flow is not accelerating in a way that simply matches the new infrastructure. Prefect Inspector José Contreras Hernández, regional head of Chile’s investigative police, said: “In 2024, we had around 2,460 attempts, but in 2025, there was a significant decrease to 1,746.” He added that the most significant increase officials have seen has involved attempts to leave Chile “irregularly,” which he attributed to migration policies and the change of government.
He also pointed to immediate short-term shifts around Arica, saying that in the first four months of the year, patrols thwarted nearly 500 attempts to leave the country illegally in Arica y Parinacota, compared with just 33 attempts in all of 2024. Sayes said border deterrents would be “continuously reviewed,” adding that crews would have to keep an eye on where traffickers and contrabandists cross and maintain the trenches so they do not crumble or fill with sand.
Even while officials describe declining illegal entry attempts, they have acknowledged ongoing enforcement challenges connected to the barriers themselves. Sayes said that on another section of the border trench, two Bolivian citizens were detained for trying to fill in the ditch to make it passable.
Chile’s government has also moved toward changes in the legal framework to align enforcement with the tougher posture. Entering the country illegally is not currently a crime in Chile, but Kast’s administration has sent two bills to Congress that would criminalize illegal entry and limit immigrants’ access to social security benefits.
Still, questions remain about how much trenching across short stretches of Chile’s more than 4,800 miles of porous borders can deter migration, drugs, or contraband over time—particularly as desert winds already blow sand back into trenches. With the program’s first phase now under way, the key test may come down to whether barriers that can be dug—and must then be maintained—reduce crossings in practice or merely shift routes elsewhere.