Customs and Border Protection won’t let me ride in their blimp. Hovering dreamily above the desert’s horizon, it’s as alien to the landscape as a Macy’s Thanksgiving Day Parade float—Snoopy-like in proportion—that broke loose from its tethers on Sixth Avenue and rode an arid breeze all the way to West Texas.

It turns out no one can ride in the blimp, because it isn’t a blimp at all. According to Bill Brooks, the CBP spokesperson for the Big Bend sector, it’s a Tethered Aerostat Radar System (TARS), an unmanned aircraft with a constitution considerably less cheery than Snoopy’s.

Moored somewhere between the tiny Far West Texas towns of Marfa and Valentine, the TARS is equipped with a 2,200-pound radar that can detect any low-flying aircraft within a 200-mile range. One of eight of the CBP’s “eyes in the sky” spanning the southern border of the U.S.—three of which reside in Texas—its purpose is to catch any narcotics that might be traveling across that dividing line.

On balmier days, it floats up to 10,000 feet in the air and appears as a faint silhouette against the limitless blue. But when the wind rushes through the broad, barren terrain, sending dust devils pirouetting skyward, the airship remains grounded. For those who venture out to this part of the state, the TARS is a surreal sight to behold. But for people who have lived here for long enough, it is a perpetual, if enigmatic, reminder that they’re being watched.

In the Rio Grande Valley, where the CBP recently deployed tactical aerostats—which are balloon-like structures smaller than the TARS—the bullet holes are the first hint that they aren’t retired parade props.

That’s because these very same aerostats once hung above a similarly stark terrain in Iraq and Afghanistan. Like the TARS, the tactical aerostats float over the landscape anywhere between 1,000 and 5,000 feet in the air. But unlike the TARS, their gaze is downward, monitoring ground traffic. The tactical aerostats are just one part of a broader initiative, known as the Department of Defense Reuse Program, in which excess military technology from our wars in the Middle East is used for domestic purposes. There, the aerostats’ surveillance technology was used to help detect improvised explosive devices. Here in Texas, they are used to find people.

The CBP removed the radars from the aerostats and retrofitted them with cameras to provide aerial views of the terrain and locate trails that might be used as migrant routes, or as drug smuggling corridors. “In the Rio Grande Valley, they were a game-changer,” said Dave Pauling, a strategy advisor for the Office of Technology Innovation and Acquisition within the CBP. “We found trails we didn’t know existed before; we were able to watch some things we didn’t know existed before.” Pauling’s office determines the viability of military equipment along the border, and since 2012, everything from night vision goggles to laser range finders and surveillance drones have made the journey down to the border.

This is all fueled by an overhaul of our Fourth Amendment rights. Since the events of September 11, 2001, the Fourth Amendment has undergone enough revisions in the name of security to render our right to privacy virtually obsolete in some parts of the country—most of all, at our borders. (Should our right to bear arms be undermined by comparable modifications, it would likely incite a riot among Second Amendment supporters. Ironically, the same far right faction that supports the sanctity of the Second Amendment is the very same political demographic that bolsters this heightened form of “security” that infringes on our Fourth Amendment rights.)

The Air and Marine Operations, another affiliate of the CBP, has already implemented larger drones in several areas along the border, though Pauling would not say where, exactly. And the CBP hopes to start using small, mobile drones that can be manned by officers, just as soon as they conduct a feasibility study with the U.S. Army later this year.

Surveillance is key to the CBP’s strategy at the border, but you don’t have to look to the skies for constant reminders that they’re there. Internal checkpoints located up to 100 miles from the border give Border Patrol agents the legal authority to search any person’s vehicle without a warrant. It’s enough to instill a feeling of guilt even in the most exemplary of citizens. For those commuting daily on roads fitted with these checkpoints, the search becomes rote: the need to prove one’s right to abide is an implicit part of life.

Despite the visible cues, it’s still hard to figure just how all-seeing the CBP’s eyes are. For one, understanding the “realities” of border security varies based on who you talk to.

Esteban Ornelas—a Mexican citizen who was charged with illegal entry into the United States in 2012 and deported shortly thereafter—swears that he was caught was because a friend he was traveling through the backcountry with sent a text message to his family. “They traced the signal,” he told me in his hometown of Boquillas.

When I consulted CBP spokesperson Brooks and senior Border Patrol agent Stephen Crump about what Ornelas had told me, they looked at each other and laughed. “That’s pretty awesome,” Crump said. “Note to self: develop that technology.”

I immediately felt foolish to have asked. But when I asked Pauling that same question, his reply was much more austere: “I can’t answer that,” he said, and left it at that.

The CBP is generally reticent about their security strategy, especially when it comes to specific details about their technology. Disclosing that information could potentially undermine their security efforts.

So that I happened to find the location of one of the CBP’s sensors was purely an accident. One evening during an already oppressively hot spring, with a friend’s dog in my care, I decided to step away from my desk and take her for a walk. The dog, Susan, and I made our way toward the Rio Grande, the international boundary that lies between the United States and Mexico and is no more than two miles from my house in the 6,000-small border town of Presidio, Texas.

Here, the Rio Grande defies its name. I stood before the narrow band of stagnant, olive-colored water, and pondered that it would take no more than a few freestyle strokes to get to the other side. The bank was a ten-foot climb from the river itself, and I watched the few bubbles that lingered on its inert surface move inches before turning back.

On my return, I spotted a Border Patrol vehicle, and a young agent I hadn’t seen previously emerged. “Sara?” he asked me—my legal name, which he’d apparently pulled from running the plates on my car that was parked at the trailhead. “Sasha,” I corrected him.

The agent informed me that I had tripped the sensors somewhere along my walk, and that agents were obligated to respond to these alerts. I was shocked. I hadn’t seen a sensor at the riverside, and suddenly, I felt that the Border Patrol was omniscient. In that moment, trying to summon the only act of agency I felt I had in a situation that was largely out of my control, I decided that I would make that same walk to the riverbank as often as I could.

Later that week there was a knock at my door in the middle of the night. Though I’ve now lived in this part of West Texas for nearly two years, as a young woman who grew up in Queens, New York, I will never grow accustomed to unannounced home visits, which are seemingly customary in the country. When I first moved to Far West Texas, I felt a thrill in not locking my doors. Now, I don’t think twice about it. But some essential survivalist part of me—the part that grew up in an urban jungle where the cardinal rule is that you cannot, must not, trust anyone—still assumes that if someone arrives unannounced, they probably have bad intentions.

I was on the phone with my father at the time, who, a New Yorker to the bone, had the same gut reaction: “Who’s showing up at your door at this hour?” I spoke in a whisper and, with my father still on the line, as though his presence some 2,000 miles away in New York City would protect me, I peeked through my curtains to find a uniformed officer standing outside.

It was the same officer I had confronted on my walk to the river. In the split second it took me to open my door, I wondered what I had done wrong. But no—he had come to inform me that some suspects he and his fellow agents were after had gotten away, not far from my house. “You might want to lock your doors,” he told me, adding, “I came out because I know you live out here alone.”

In my flustered alarm, I asked him if he could tell me anything else. He could not. Could he at least tell me if these suspects were armed? He could not. Instead, he pointed to the phone receiver I still held to my ear, in which my dad was yammering his anxieties about me living alone in a place so far away. “Who is that?” he asked.

“It’s my father,” I said, shocked by how cavalier he was and wondering if this Border Patrol agent had forgotten that it was he who had shown up at my door. “You just scared the shit out of me,” I told him.

He left, and I locked my doors as he’d recommended, but I remained shaken, alert to every small sound outside my window. I thought I was safe, and in virtually every aspect of my life here in West Texas, it seemed I truly was. In New York, I had witnessed brutality, filth, and despair. On many occasions in the city I had been forced to reckon with my deepest fears.

In Presidio there was almost none of that. The small border town had welcomed me, an outsider, with open arms, and it was the sort of small community in which people held one another accountable. It was a place where violent crime was unheard of, and the theft of a couple of cars one year made front-page news. Unsurprisingly, the culprit was an outsider.

After nearly two years of living and working as a reporter on the border, I’d become acutely aware that the “border narrative”—one of lawlessness and violence—was a far cry from my experience. According to CBP statistics, most of Border Patrol apprehensions in the Big Bend Sector—some 5,031 total in the 2015 fiscal year—were cases of migrants crossing the border illegally, the vast majority unarmed. Of that number, a total of 1,646 apprehensions were cases of family units and “unaccompanied alien children” who had crossed illegally. There were two assaults that year.

I was sure that I was safe, but the man in the uniform suggested that I was not. He was doing his job—in fact, even going beyond the call of duty by coming to my house. Perhaps he thought warning the young woman who lived alone was the gallant thing to do, given the circumstances. But ironically, the moment at which I felt most fearful was when he showed up at my door. He had intruded upon my privacy in a way that challenged my own perceptions to their very core, and disturbed the firmament of my free will.

I realized I wasn’t scared of whatever lurked outside my house. I was scared that the term “outside” had become a meaningless designation.

But I had felt this fear before. It was the same feeling I’d had while I was living in Iran years before, when one night, someone rang my doorbell.

The circumstances were different: I had previously lived in Iran for almost a year, and had visited family multiple times throughout my whole life. My mother had emigrated from the country before the Islamic Revolution, but most of her family still lived in Tehran. I loved my culture and its vast and storied history. I loved the country and the creative ways in which its citizens challenged the theocratic regime. Most of all, I loved challenging people’s misconceptions (there were too many to count) of the place.

But there was an ugly side too. Rumors of the regime’s technological capabilities, the breadth of their surveillance, were enough to inspire a sometimes overwhelming sense of paranoia, where the perpetual fear of being monitored and caught dictated our actions and behavior. My peers and I had used virtual private networks (VPNs) to bypass the extensive censors on the Internet, and yet I still censored myself when communicating with friends and family via social media or e-mail.

Once, when I was talking to my mother on the phone, her voice cut out for several seconds before it came back. The previous five seconds of our conversation played back in a warbled blur as though someone had recorded us, then pressed a fast-forward button. At an Internet cafe in a wealthy Tehran neighborhood, two German expatriates, who spoke candidly about the government, had not only turned off their phones, but also had taken the additional precaution of removing the battery packs from them.

Moments like these wove together in a fraught pattern that set me on edge. It seemed the fear of not knowing how much the government knew and what they were capable of was part and parcel of the current regime’s attempts to control its populace, a fear I am viscerally reminded of even as I write this now, knowing I will inevitably return to the country to visit again. Not to mention, I embody the thing that all authoritarian regimes hate most: I am a journalist.

Four years ago, someone rang the doorbell to my mother’s Tehran apartment—where I was once again living alone—in the dead of night, and I shrank with fear. My heart resounded within its walls, and I could not even persuade myself to get out of bed to check the video monitor that showed a view of the front door.

I lay immobilized, and waited while my pulse blared in my ears. Minutes passed and nothing happened. No one came. It was possible that someone had mistakenly rung my doorbell, or sounded it in passing for fun, or that something had inadvertently triggered it. There were a whole number of possible scenarios, any of which would have been plausible. But one thought persisted: I felt certain I was being watched. And not just by anyone, but by an entity much bigger and more obscure than myself.

I was convinced there was a clear reason that someone had rung my door when no one else was awake. This intruder—whether real or not—not only punctured the inviolability of my home, but also brought it into a new and psychological dimension. I felt that I had lost all control. I didn’t sleep until the sun rose again.

And here I was, years later in Texas, lying alone in bed with those same fears. How did the Border Patrol agent know where I lived? And how did he know I lived there alone?

And when the aerostats hang thousands of feet above us, what do they see? Do they see trails upon which smugglers might backpack their contraband? Do they see clusters of migrants journeying along the parched terrain?

Or do they see networks of people living their lives with the obedient tenacity of ants who forge lines within the structure of their farm? Do they see a girl with a dog walking to the river’s edge?

The next morning, I took Susan for a walk again. I traced the same course to the river and lingered for the same number of minutes at its edge. When I returned to my car, there was no Border Patrol vehicle waiting for me. The path back to my house was clear. I parked my car, walked into my house, and shut the door behind me, unlocked.