There was an elephant in the room — a big, beautiful, concrete elephant — at the Border Security Expo in Texas last week, a gathering of industry and immigration officials, where Trump’s border wall was discussed in tones of measured exasperation. While the conference attendees seemed largely pleased with the president and the public’s attention to their mission, the wisdom of a wall is a conversation that most of these people have been having for over a decade.

“We already have about 650 miles of various types of wall. We’ll put the wall where it makes sense,” said Randolph “Tex” Alles, the acting deputy commissioner of U.S. Customs and Border Protection, in his opening remarks, echoing comments by many former border officials. “It being a contiguous or continuous barrier across the entire border is not what the secretary [of Homeland Security] is talking about.”

“I don’t think my county needs a border wall. I’ve got 200-foot bluffs on my border,” Sheriff Joe Frank Martinez of Val Verde County in Texas remarked on a panel with other local law enforcement. What’s more, local ranchers “don’t want the federal government on their property” to build a wall.

The chief of police in San Antonio, William McManus, refused to discuss the matter at all. “It’s all been beaten to death,” he said.

The man in charge of actually figuring out how to buy and build the wall, CBP’s top procurement official, Mark Borkowski, spun the concrete prototypes that will be constructed in San Diego this summer as an option “in the toolkit.”

“Now look, I bet if we took a poll here, each of us would have an opinion of whether we think that’s a good idea or not,” Borkowski said. “Each of us would have an opinion of whether that’s the way the country should project itself to the world or not. There are pretty good arguments either way.” But the president had ordered them to “go get a wall,” and so something had to happen.

This is not the first time that political zeal for a barrier has overwhelmed even the aspirations of immigration hard-liners at CBP. “When you listen to the big beautiful wall narrative … that plays well with the base,” said Jayson Ahern, who was a commissioner at CBP during the George W. Bush administration, when Congress passed the Secure Fence Act, which called for sealing off the southern border with double-layered fence. Ahern explained that his office “had to negotiate hard to dial that down to what is actually required.”

What is required, of course, depends on what you’re trying to do. Is it possible to arrest every person who puts a toe across the line on the map? For years, the idea was “persistent impedence,” in Borkowski’s coinage — in other words, just make it more difficult. Under Trump’s order, the goal has shifted to “total operational control,” meaning the prevention of all unauthorized crossings.

Even if a wall could be built, it wouldn’t automatically achieve that. Agents have got to be able to see when someone is attempting to cross it or tunnel under it — or vandalize it, as a vendor asked worriedly during one of the expo sessions. A wall, said Alles, “slows people down, it doesn’t stop them, without agents on the ground, without aircraft, without technology.”

Borkowski advised the company reps in the audience to “pay attention when you hear that word system, because that’s our way of saying there’s got to be technology and roads and lights and other stuff.”

CBP already has some components of a “virtual fence.” The agency is proud of its radar blimps (inherited from the Air Force), its fixed towers equipped with various types of sensors and cameras across the edge of Arizona, and video surveillance systems.

Vendors on the expo floor offered more: sensors to identify the vibrations of digging, gunshots, or footsteps; a variety of “hardened” fences; as well as drones, radar to catch drones, cameras, floodlights, hand-held fingerprint readers, facial-recognition software, license-plate readers, and rubber bullets.

A duo of Border Patrol agents from Arizona, who asked that I not use their names because they were not authorized to speak with the media, were there to look at the options and request demos for their office. The men claimed that in the past, the mostly Mexican immigrants that they encountered would quickly submit to arrest.

“They’d sit down when we tapped them on the shoulder. Now I grab two guys and the others take off. They don’t think we’re real cops,” one of the agents said. With more cameras and the like they can track and head off the others, they said. “Technology is helping with that. I can chase the other guys after I get these two.”

In another room, two consulting firms, DeLoitte and Black & Veatch, tried to pitch a techno-utopian vision of border control, with transnational “smart cities” where every shipment is tagged with RFID tags and travelers are quickly identified by biometrics. “It’s a global corridor, all secured, all tracked,” said a Deloitte consultant.

Antonio Trindade, associate chief of enforcement and technology at the Border Patrol, offered a contemporary and more unsettling take on such biopolitics. His agents have been collecting fingerprints since 1994, running “10 print rolls” against databases of criminal and immigration offenders from the FBI and DHS. Patrick Nemeth, head of the Identity Operations Division at DHS’s Office of Biometric Identity Management, noted that his agency’s IDENT is the second-largest biometric database in the world, after India’s controversial national identity system. Border Patrol agents also often collect eye scans. “We love iris,” Trindade said, adding that “a lot of the folks we’re apprehending are working in masonry and their fingerprints are very worn down.”

CBP, along with Northern Command and the Department of State, also supports a program to help Mexico collect biometrics at Tapachula, near the border with Guatemala. The program would allow U.S. authorities to track “trends of migration coming through Central America up to the border,” Trindade said. “So it’s a great time for biometrics.”

Despite the visiting officials asking “industry to help” with their newly invigorated mission, the vibe on the expo floor was not quite a bonanza. The wall, among its other drawbacks, is largely unfunded. The Border Patrol already struggles with new recruits, and it is supposed to conjure 5,000 more that will be needed to respond to whatever a new wall system trips.

A salesman with a local security firm from San Antonio said it had been quieter than he expected. “Waitin’ on the money,” he said. A representative from McQ, a company that makes ground sensors (one is called iScout, advertised as “the next scouting legend” with a painting of a Native American) was also not terribly impressed. “Everyone’s trying to get in on it, and it’s not a huge pot,” she said. Most of her contracts were with the military; with DHS, “these guys don’t quite know what they want yet.”

Borkowski, the CBP procurement official, suggested that it wasn’t really the technology or infrastructure that would change so drastically. He began his presentation with a chart showing the sharp drop in arrests on the southwestern border since Trump took office. The only thing that explained that, he said, was “a change in the policy we advertise about how we’re going to handle border security and how we’re going to deal with people who came to the border.”

There are other signs that Trump’s rhetoric is doing border agents’ job for them: increased absences from border schools, a decrease in crime reporting in Latino neighborhoods linked to fears of being caught by immigration authorities, and undocumented families staying away from social programs. If the goal is to terrorize communities, you don’t necessarily need a wall.