The US military is testing high-altitude, solar-powered balloons to “provide a persistent surveillance system to locate and deter narcotic trafficking and homeland security threats,” according to documents filed with the US Federal Communications Commission (FCC).

So far, 25 balloons, equipped with sophisticated radars that can be used to track vehicles or boats in a 25-mile field, have been launched from South Dakota and will pass through parts of US states Minnesota, Iowa, Wisconsin and Missouri before being grounded in Illinois. The balloons are traveling at altitudes as high as 65,000 feet and are equipped with a video capture system called Gorgon Stare, which was developed by the US military and described by the US Air Force as a “wide-area surveillance sensor system.”

The balloons are being flown by the US Southern Command, one of the 10 Unified Combatant Commands in the US Department of Defense, and will be able to communicate with each other through networking technologies. While some of the flights were approved by the FCC last year, the most recent FCC filing made by aerospace and defense company Sierra Nevada Corporation appears to approve a set of flights taking place between mid-July and September.

“What this new technology proposes is to watch everything at once. Sometimes it’s referred to as ‘combat TiVo’ because when an event happens somewhere in the surveilled area, you can potentially rewind the tape to see exactly what occurred, and rewind even further to see who was involved and where they came from,” Arthur Holland Michel, the co-director of the Center for the Study of the Drone at Bard College in New York, told the Guardian.

However, a senior policy analyst at the American Civil Liberties Union (ACLU) raised concerns over the mass surveillance operation.

“We do not think that American cities should be subject to wide-area surveillance in which every vehicle could be tracked wherever they go,” Jay Stanley told the Guardian.

“Even in tests, they’re still collecting a lot of data on Americans: who’s driving to the union house, the church, the mosque, the Alzheimer’s clinic,” he added. “We should not go down the road of allowing this to be used in the United States, and it’s disturbing to hear that these tests are being carried out, by the military no less.”

It is yet unclear whether the balloons are currently being used for narcotic or counter-terrorism investigations and whether the data collected by the balloons will be deleted or potentially provided to other federal or local agencies.

“[We would like to know] what they are they doing with that data, how they are storing it, and whether they are contemplating deploying this in the US,” Stanley said. “Because if they decide that it’s usable domestically, there’s going to be enormous pressure to deploy it.”