The U.S. military is flying surveillance aircraft along the southern border with Mexico to collect intelligence and conduct reconnaissance, according to U.S. defense sources familiar with operations at the border.

The U-2 spy planes have been joined by P-8A Poseidon aircraft and are flying the length of the border.

The Navy P-8A and U-2 Air Force aircraft have been deployed to the border since President Donald Trump issued a Day One executive order declaring a national emergency there, and have been flying about one sortie per day.

Fox News is told this is not the first time that the U.S. has flown this kind of surveillance along the border.

U.S. Navy sailors, assigned to Patrol Squadron (VP) 40, conduct flight operations along the southern border aboard a P-8A Poseidon aircraft on Jan. 31, 2025.  (U.S. Navy photo by Mass Communication Specialist 2nd Class Andy Anderson)

The U-2 “provides high-altitude, all-weather surveillance and reconnaissance” during the day or night and “delivers critical imagery and signals intelligence to decision makers,” the Air Force writes in its description of the aircraft.

The Navy describes its P-8 Poseidon as a “multi-mission maritime patrol and reconnaissance aircraft conducting long-range anti-submarine warfare, anti-surface warfare, intelligence, surveillance and reconnaissance.”

A P-8A Poseidon aircraft, assigned to Patrol Squadron (VP) 40, rests on the runway at Davis-Monthan Air Force Base, Arizona, between operations along the southern border on Jan. 31, 2025. (U.S. Navy photo by Mass Communication Specialist 2nd Class Andy Anderson)

There have been discussions at the Pentagon about how to reassure the public that the spy planes are not gathering intelligence on U.S. citizens, Fox News is told. If the aircraft inadvertently collects intel on American citizens who may live at the border or who are crossing at legal check points, operators are required to erase such data.

Most fentanyl trafficked into the U.S. is smuggled in by American citizens at legal ports of entry, and very little is smuggled across by migrants entering illegally, given their likelihood of being intercepted, according to several CATO Institute reports in the past few years.