ARICA, CHILE — Chilean military excavators have begun digging an 11-kilometre trench three meters deep along the country's northern border with Peru, part of President José Antonio Kast's 'border shield' plan. Kast traveled to Arica in March to announce the initiation of the plan, which aims to seal vulnerable stretches of the 1,200-kilometre border Chile shares with Peru and Bolivia across the three northernmost regions in the Atacama Desert.

"We have made 53.6% progress, which means about six kilometres in this area," said Cristián Sayes, Kast's delegate in the northernmost administrative region. A second trench higher in the mountains will stretch seven kilometres, and two additional ditches are being dug further south on the border with Bolivia.

The first phase of the plan includes several short trench sections along the most exposed parts of the frontier, followed by the deployment of surveillance equipment. The original proposal had included erecting five-metre walls in some areas.

"In addition to ditches, fences and walls, there will be thermal and infrared cameras, sensors, radars and drones with facial recognition cameras – all operating 24 hours a day," Sayes said. "This is a constant and dynamic job, we will have to keep an eye on where traffickers and contrabandists are crossing, and we will have to maintain the trench so that it doesn't crumble or fill with sand," he added.

"The ultimate goal is to have constant control of the border so that we can stop illegal migration once and for all, but also confront drug trafficking, smuggling, and human trafficking," Sayes said. Tank traps from the 1970s line the landscape on both sides of the highway near the trench, and a section of desert nearby still contains anti-tank mines from that decade. Peruvian border police sit under wind-torn blue awnings near the boundary, where Chilean soldiers patrol.

"In 2024, we had around 2,460 attempts, but in 2025, there was a significant decrease to 1,746," said Prefect Inspector José Contreras Hernández, regional head of Chile's investigative police force. In the first four months of this year, border patrols in Arica y Parinacota thwarted nearly 500 attempts to leave Chile illegally, compared with 33 attempts in all of 2024. "The most significant increase we have seen is actually in attempts by people to leave or try to leave the national territory irregularly," Contreras Hernández said.

Two Bolivian citizens were detained on a section of the border trench for attempting to fill in the ditch to make it passable. Kast, who won 58% of the vote in the December runoff election, has deported 40 people on a single outbound flight. Entering Chile illegally is not a crime under current Chilean law, and the Kast government has sent two bills to Congress that would criminalize illegal entry and limit immigrants' access to social security benefits. Official estimates place the number of migrants living illegally in Chile at 336,000.