Mysterious drones have been buzzing around America’s most sensitive military sites, and guess what? According to a new report, the Pentagon has acknowledged that there isn’t much they can do about it.

Unidentified drones have been spotted flying over military bases in Virginia and Nevada for the past year. Some of these bases are pretty important, including the home of SEAL Team Six and Naval Station Norfolk, which is the largest naval port in the world.

You’re probably wondering, “Why don’t they just shoot these things down?” It’s a Good question. The answer? Federal laws.  These laws prevent the military from blasting drones out of the sky because of the potential danger to troops and civilians. So, while these drones keep flying around, there’s not much anyone can do except watch and hope they aren’t taking too many pictures or gathering important information.

Authorities have made it clear that this isn’t just a case of someone messing around with a hobby drone. These drones are way too coordinated and high-tech to be the work of a bunch of amateurs. So, who’s behind them? Well, that’s the million-dollar question.

A little hint may have come last January when a Chinese student at the University of Minnesota, Fengyun Shi, got caught flying a drone near Langley Air Force Base. Shi, 26, didn’t exactly cover his tracks either—his drone got stuck in a tree. He bailed on the whole situation and flew to California the next day, leaving the drone behind. Neighbors near the Newport News Shipbuilding yard noticed a guy flying a drone near the site around the same time, which was, of course, January 6. (Weird coincidence, right?)

Well, that drone eventually fell out of the tree, and guess who got ahold of it? The FBI. Surprise, surprise, they found photos of Navy ships docked at the base on it. Shi was arrested a week later, right as he was about to board a one-way flight back to China. Prosecutors didn’t waste any time charging him with unlawfully taking photos of classified naval installations—this was the first time a drone was involved in such a case.

Shi tried to play the “I’m just a tourist on vacation” card, claiming he was flying the drone just for fun. But the judge wasn’t buying it. Magistrate Judge Lawrence Leonard shut that down, and Shi ended up pleading guilty to espionage charges on October 2.

Shi’s case was not a one-off case. Similar swarms of drones have also been spotted near Edwards Air Force Base in Nevada, which is another highly sensitive and important military site. While the Defense Department hasn’t provided any information about who might be behind these mysterious drone sightings, it’s safe to say that they’re not pleased with the situation. The fact that these drones keep appearing over such crucial locations is definitely a cause for concern, and officials are likely working hard to figure out who or what is responsible.

Shi’s attorney, Shaoming Cheng, told the Wall Street Journal, “If he was a foreign agent, he would be the worst spy ever known.” He’s got a point. Getting your drone stuck in a tree and leaving it behind isn’t exactly James Bond material. Shi may not be great at spying, but that doesn’t mean the other drone operators aren’t. The fact that these drones keep appearing over military bases is definitely worrying.

For now, the mystery of the drones remains unsolved. Are they from a foreign government? Maybe a supervillain obsessed with military bases? No one really knows. What is clear is that until the Pentagon figures out how to deal with these flying intruders, they’ll keep showing up where they don’t belong.

And hey, maybe next time, the spy of the hour won’t leave his drone stuck in a tree for the feds to find. Just a thought.