(NewsNation) — Texas officials are reporting declining numbers of people unlawfully crossing the southern border, something Republican Texas Gov. Greg Abbott has attributed to increased enforcement efforts under Operation Lone Star in a recent interview with NewsNation’s Ali Bradley.

John Sandweg, who was the acting director of Immigration and Customs Enforcement under former President Barack Obama, said on “NewsNation Now” that while there’s “no doubt” Operation Lone Star has made an impact, migration has shifted for a number of other complicated reasons as well.

“I would be careful to sit there and say all of this is a result of the enforcement efforts Texas is taking,” Sandweg said. “It’s too simplistic to simply say, well, Operation Lone Star’s kicked the traffic over there.”

As part of Operation Lone Star, which was launched in March 2021, Abbott deployed the Texas National Guard and Texas Department of Public Safety to the 1,200-mile southern border with Mexico. In addition, the state has spent millions on installing concertina wire rolls and putting buoy barriers across the Rio Grande. Now, Abbott told NewsNation, he wants to expand the buoys.

Even with these measures, Sandweg said, people are still crossing illegally, and cartels still have a “very serious influence” on what happens at the Texas border.

“The problem’s a lot more complicated than simply putting razor wire or buoys in a river,” Sandweg said.