“After you get out [of the military], you want to continue to help out … I felt that doing the most good would be actually coming down here and doing something that actually affected America instead of fighting a war somewhere else,” said Kyle Erickson, 31, of Wyoming, who said he served two tours in Afghanistan and one in Iraq as an Army combat engineer.

“It says in the name ‘recon.’ We’re out there to watch. And, like, we did. We watched. We stopped their operation from doing what it needed to do last night. To me, that’s the biggest win there is, not necessarily us capturing people,” he said.

The mountainous strip is traversed by undocumented migrants on foot and drug mules toting marijuana in makeshift backpacks, sometimes accompanied by armed guards to ward off bandits. Erickson said he initially had a legacy get-’em response when he set off after a group of border crossers but took a step back.

“These people are not at war with us, and most of them are doing it to make a living or have a better life. It’s not necessarily about they’re here to hurt me, because 90 percent of them are not. So I’m not trying to pull a weapon on them every time I hear a noise,” he said.

Puerto Rico–born Manny Vega, 29, said he did four tours in Iraq during his nearly nine years of service with the Marines. He felt the AZBR operation, his second, gave him a chance to use his skills to uphold U.S. sovereignty at the border while laying down fresh memories of his service that left him medically retired with post-traumatic stress disorder and traumatic brain injury.

The camaraderie of carrying out the operations with other combat veterans also helped him come to terms with the trauma of a bomb blast in Iraq in 2004 that injured him and killed his comrade Nachez “Little Fawn” Washalanta II, whom he commemorates with a wristband.

“I have nightmares. I do have thoughts of my friend dying. I do have thoughts of being blown up with an IED,” he said. “For me, it is therapeutic to come down here and join my fellow veterans … This is making new memories for me.”

The paramilitary group’s border reconnaissance activities have sparked concern among some residents in the nearby town of Arivaca (population 700), about 15 miles away over the rugged mountains, which has a bloody recent history of vigilante violence.