MADERO, Texas — Breitbart News followed Rio Grande Valley Sector Border Patrol agents into the brush to explore a busy network of Gulf Cartel smuggling trails on the U.S. side of the Rio Grande. The tour of the trails by a Border Patrol supervisor came during a river patrol that led to the apprehension of three Chinese nationals.

While conducting a tour of the Rio Grande, McAllen Station riverine agents received a call about a group of migrants being smuggled across the river from Mexico. Breitbart News Editor-in-Chief Alex Marlow and Border and Cartel Chronicles Projects Director Brandon Darby followed the agents into the brush where they witnessed the rough network of cartel smuggling pathways on U.S. soil.

“This is a cartel trail — in Texas,” the Border Patrol supervisory agent explained. “This is what they utilize to smuggle their goods, whether it is narcotics or aliens.”

The agent explained that various smuggling groups in Mexico pay the cartel for the right to cross their cargo across the river in this region.

“The cartel has full authority of what can come in and out,” the agent said. “Whatever has been paid is what’s coming through. This is their trail — this is an alien smuggling organization’s trail.”

“Connected to the cartel?” Darby asked.

“Connected to the cartel,” the agent responded. “Because the cartel allows them to use it.”

The referenced cartel is the Reynosa faction of the Gulf Cartel. Border Patrol officials previously told Breitbart News that this transnational criminal organization controls all smuggling routes through this area. This faction is covered frequently by Breitbart Texas and the Cartel Chronicles project.

The veteran agent explained that cartel gatekeepers on the south side of the river control when and where select smugglers are allowed to cross. He said a network of scouts on the Texas side of the river track Border Patrol activity and provide intelligence information to the cartels on when it might be safe to cross.

“These trails have got some work,” Marlow commented after observing the maturity of the trails.

“They’re heavily used,” the agent replied.

Darby asked if local residents have access to this area. “This is a park; it is federal land,” the agent said. “It’s highly unlikely as it’s fairly dangerous down here. If you’re a local, you really have no business down here.”

Marlow asked the agent about the likelihood of detecting the smugglers. “We have sensors and ‘Drawbridge’ cameras. They’ll notify the agents on the boats and we’ll get behind them and try to catch what we can.”

Operation Drawbridge is a Texas Department of Public Safety border security program that provides technology and manpower to assist the federal government’s efforts to secure the border.

The agent explained the Reynosa faction of the Gulf Cartel utilizes juvenile smuggling guides to move the migrants through the thick brush. He said the U.S. cannot prosecute foreign juveniles so they return multiple times.

“The best thing we can do is get a paper trail on them for smuggling and when they turn 18 possibly prosecute them,” he stated. The agent said the guides range in age from 12 to 17.

During this boat tour of the Rio Grande, a smuggling incident took place. Breitbart News witnessed the apprehension of three Chinese nationals and the arrest of their U.S. citizen alleged smuggler, who picked them up after they made their way through these very trails.

The boats operated by these Border Patrol riverine agents are owned by U.S. Customs and Border Protection’s Air and Marine Operations McAllen Branch.