In an attempt to secure America's southern border, President Donald Trump established a series of "National Defense Areas" in New Mexico, Arizona, and Texas.

Yet in a move which is sure to leave Trump furious, a judge opted to dismiss charges brought against 98 illegal aliens who entered one of the areas. 

Judge: No proof that migrants knew they were entering restricted area

According to ABC News, that decision was issued this past Wednesday from U.S. Magistrate Judge Gregory B. Wormuth, who concluded that prosecutors failed to prove the migrants knew they were entering a restricted location.

Government lawyers pointed out that warning signs written in both English and Spanish have been put up at regular intervals throughout the 170-mile-long New Mexico National Defense Area.

However, Wormuth found no proof that any of the defendants had actually seen the signs given the region's often mountainous terrain.

"Beyond the reference to signage, the United States provides no facts from which one could reasonably conclude that the Defendant knew he was entering the NMNDA (New Mexico National Defense Area)," he wrote in his 16-page ruling.

"Consequently, the Criminal Complaint fails to establish probable cause to believe that Defendant knew he/she was entering the NMNDA," the federal judge went on to add.

National Defense Areas typically run 60 feet from the Mexican border

All of the 98 migrants had been charged with one count of violating a security regulation and one count of entering military property for an unlawful purpose.

Thanks to Wormuth's ruling both of those charges have been dismissed. Each migrant also faces a single count of entering the U.S. illegally, and that charge remains.

ABC News noted that the restricted zone begins at the Mexican border and typically runs about 60 feet into the United States, although some sections are wider.

It was established last month as an extension of Fort Huachuca, a military installation which is located in the southeast corner of Arizona.

Military has detected more than 150 "unauthorized trespassers"

Maj. Geoffrey Carmichael serves as a spokesman for Joint Task Force Southern Border, and he told ABC News that military personnel have thus far detected over 150 "unauthorized trespassers."

Carmichael explained that those individuals were subsequently apprehended by U.S. Border Patrol agents. He added that soldiers have not detained any migrants.

Trump signed a memorandum in April which established National Defense areas "for sealing the Southern border of the United States and repelling invaders."