Israel isn’t keeping its latest advanced spy drone for itself. It’s going south of the U.S. border, probably purchased by the Mexican government. The cartel war may be about to get a lot more robotic.

For some reason, Israel isn’t disclosing which “Latin American government” bought an unknown number of unarmed Hermes 900 drones for $50 million. But Danger Room pal Paul McLeary of Aviation Week suspects it’s Mexico, and has spotted documents from Mexico’s finance ministry that might prove it. One document dated Dec. 20, 2011 and available on the ministry’s website, sought to fill an order worth about $50 million for “unmanned aircraft, ground segment and additional payloads for the Federal Police.”

The price happens to match an announcement by Israeli defense firm Elbit Systems in January to supply an order for the Hermes 900 to “a governmental office of a country in the Americas.” Elbit Systems isn’t confirming it, but McLeary also reportedly obtained another document from the ministry regarding the “acquisition of two Unmanned Aerial Vehicles 900, ground command-and-control system and additional payload.”

So chances are that the Hermes 900 is headed for the skies above Juarez. It would hardly be the first drone deployed against the cartels. But it’s still a “huge upgrade,” writes McLeary: Mexico’s military uses at least two Israeli Hermes 450 drones and the federales have more than a dozen smaller, hand-launched “micro-UAVs.”

The Hermes 900 has more than twice the endurance of the 450. It can loiter for a maximum of 40 hours compared to the Hermes 450’s meager 17 hours. And it tops out at 15,000 feet higher than the Hermes 450, giving the drone a maximum ceiling of 33,000 feet.

That means Mexico’s security forces will be able to snoop on the cartels for longer, at higher altitudes and be able to do so quietly, without help from the gringos. The U.S. openly operates drones — including the Hermes 450 — along the border to track drug traffickers, and covertly operates the Predator and Global Hawk within Mexico at the request of the Mexican government.

The new model Hermes has the capacity to carry “additional payloads,” but there’s no indication the robot will carry weapons. (Mexico probably doesn’t want to risk incinerating its own citizens.)

The additional drones are unlikely to be a gamechanger. But the cartels may soon feel more robotic eyes watching their moves.