Two American soldiers were disarmed and questioned by Mexican troops wielding assault rifles this month while conducting a surveillance mission on US territory near the southern border, defense officials told CNN.

"On April 13, 2019, at approximately 2 p.m. CDT, five to six Mexican military personnel questioned two U.S. Army soldiers who were conducting border support operations in an unmarked (Customs and Border Protection) vehicle near the southwest border in the vicinity of Clint, Texas," US Northern Command told CNN in a statement. “An inquiry by (Customs and Border Patrol) and (the Department of Defense) revealed that the Mexican military members believed that the US Army soldiers were south of the border,” the statement added.

US officials confirmed that Mexican troops were armed with FX-05 Xiuhcoatl assault rifles. They surrounded the vehicle and disarmed one of the Americans. According to CNN sources, both Americans surrendered "in an attempt to de-escalate a potentially volatile situation."

"Throughout the incident, the U.S. soldiers followed all established procedures and protocols," the statement read.

"After a brief discussion between the soldiers from the two nations, the Mexican military members departed the area. The U.S. soldiers immediately contacted CBP, who responded quickly," Deputy Director of public affairs for NORAD and U.S. Northern Command John Cornelio told Newsweek.

Both US soldiers reported hearing someone yell vámonos in Spanish from the Mexican side. The Americans said, the Mexican soldiers went back to their "dark blue Ford pickup truck with a tactical rack in the back." The truck departed from the area, heading westbound on the border.

After the incident, US service members alerted Customs and Border Protection (CBP) and military commanders. CBP agents responded in 10 to 12 minutes to asses the situation.

CBP agents identified footprints from Mexican troops and determined they entered into U.S. territory about 50 feet north of the Rio Grande.

Both US soldiers were attached to the B Battery, 1st Battalion, 37th Field Artillery Regiment rom Joint Base Lewis-McChord in Washington, and deployed to the southern border by President Trump in Oct. 2018.

Pentagon officials demanded an explanation from the Mexican government.

"An inquiry by CBP and DOD [Department of Defense] revealed that the Mexican military members believed that US Army soldiers were south of the border," Northern Command said while indicating that US troops were north of the border.

This incident comes at the same time as the FBI arrests a US militia leader near the border, whose team has been rounding up illegal immigrants near the New Mexico border; prompting Mexico’s Foreign Relations Ministry to express its “deep concern” that these militia groups would “drive human rights abuses of people who migrate or request asylum or refuge in the United States.” That’s a pretty rich statement from a government that evidently refuses to apologize for stepping on our soil and detaining our own soldiers.

Confusion on the border almost turned into a chaotic event that could have severely damaged Mexico-US relations. With an elevated level of American troops patrolling the border and tensions rising between both countries, the expectation of more border incidents is high.