TÁCHIRA, Venezuela — A small faction of armed civilians loyal to Venezuelan President Nicolás Maduro were patrolling a “trocha,” an unguarded illegal passage in the hills between Venezuela and Colombia, when the leader of the group told his companions to watch out for drones.

They were stationed on the border in advance of the opposition’s attempt to force aid shipments into Venezuela this weekend. But they were on the lookout for something else: signs of an invasion.

Just miles away, Venezuelan soldiers stood shoulder to shoulder on the never-opened Tienditas bridge in Cucuta, where Maduro’s blockade of shipping containers and a grounded oil tanker blocked the passage of aid into his country.

“We work together with the Venezuelan armed forces. They’re armed, and so are we,” said a member of the group, called Los Centauros _(_The Centaurs), who spoke on condition of anonymity. “They give us training: one month in the mountains, to see how it goes. Right now they’re giving us a 9mm.”

Since January, when 35-year-old Juan Guaido declared himself interim president of Venezuela in defiance of Maduro’s rule, the opposition has used the passage of badly needed aid shipments as a tool to chip away at the armed forces’ loyalty to the government.

So far, it's slow going, with only a few hundred members of the country's armed forces defecting to the opposition. But as Maduro faces mounting international pressure, a collapsing economy and an opposition dead-set on recruiting more members of the military, he’s relying on colectivos like Los Centauros to hold the line.

The term colectivo refers to any number of neighborhood communes that flourished with government support during Hugo Chávez’s presidency. Many colectivos are still active as autonomous — and unarmed — political formations, but under Maduro’s embattled rule, some of them have transformed into the government’s de facto paramilitary arm.

After the opposition’s highly publicized attempt to pass aid into the country last weekend ended in violence — when clashes between anti- and pro-Maduro groups left almost 300 injured — officials on both sides of the border are on high alert. The presence of these colectivos on the border is yet more cause for concern, and one of many signs that any international effort to penetrate Maduro’s blockade will be faced with a bloody resistance.

“If another government comes in, the hunt would begin. We’d have to hide, go to another country,” said a member of Los Centauros. “We’re defending this government until death. It’s a promise we made when we started, and we have to stand by it.”

VICE News traveled to Táchira to see how these groups are factoring into the simmering standoff on Venezuela's border with Colombia.