(NewsNation) —  Following recently released data from U.S. Customs and Border Protection maintaining more than 2 million people have crossed into the United States in a year for the first time, a major concern is now trespassers on the terrorist watch list, as at least 78 individuals on the terrorist watch list have been arrested since Oct. 1 — and 12 of those arrests were made in August alone.

It’s an issue that has also affected the Tucson sector, which has seen a 10% increase in encounters, going from 17,709 encounters in July to 19,574 in August. 

“This is kind of one of these cat-and-mouse games that we play every day here, more specifically in this area,” Jose Robert Ortiz, a Tucson sector Border Patrol agent, told NewsNation’s “Rush Hour” on Wednesday.

“There could be some people staged up right now or they could be up on that hill, but we do know for a fact when they’re standing around looking like that, there’s either something about to happen or they’re calling traffic out that’s already here that we can’t see at the moment,” he added.

Meanwhile, Nogales, Arizona, is experiencing what Border Patrol calls task saturation — which is a situation where, within an hour, nine people, coming in pairs or alone as scouts on the Mexico side of the border, send migrants across to go through the holes in the wall or climb over all at once, knowing agents can’t catch them all.

This as Border Patrol is saying they are understaffed, with 800 to 900 fewer agents in the sector since 2019.

“Their game plan is to try to see where there’s any perceived weaknesses — any areas that we are not looking,” Ortiz said. “So, for example, let’s just say there’s three units right here and we are all facing east, they’re gonna try to go west.”

Working alongside Border Patrol, Air and Marine Operations agents act as force multipliers when it comes to catching those who are trying to remain undetected.

NewsNation was able to catch up with an Air Interdiction agent named Zoe Cunningham, who said she looks for signs from the sky and also responds to calls to help Border Patrol gain the upper hand, as the terrain in Arizona is extremely difficult to navigate from the ground.

“We operate in very performance-limited areas, sometimes depending on the aircraft, the terrain, how hot it is that day. Some of these mountains are 8,000 feet tall and some of the people that we are rescuing or trying to find are very well hidden,” Cunningham said.

Air and Marine Operations agents don’t just work on apprehensions. .They aim to save lives, performing countless rescues each year in the mountainous regions where migrants get lost and are near death. 

“We do get 911 calls in that area. That is why air support is so critical to that area, because it’s going to take agents hours just to get up there to assess the patient, and that’s hours where they might be progressively getting worse and worse.”

Nogales is also where more than 5.1 million fentanyl pills have been seized since Aug. 1 by agents from the Tucson Sector field office — surpassing all other sectors along the southwest border combined.