It’s 2023. Why are militaries still using spy balloons?

The Pentagon says that a Chinese high-altitude balloon has been soaring above the U.S. this week, adding that it’s carrying surveillance equipment and is violating sovereign airspace.

Spy balloons have been around since the late 1700s, but why are militaries around the world still flying them in 2023? 

First, these high-altitude inflatables can conduct surveillance missions for a lower cost than satellites and can carry more payloads than a drone. Modern high-altitude inflatables ride on wind currents and can travel well above commercial air traffic.

Another reason: Spy balloons can travel great distances without needing to be refueled.

“It’s also a reminder of the air defense needs of the United States that today it’s a balloon, tomorrow it’s a cruise missile,” said Tom Karako, senior fellow for the International Security Program and Missile Defense Project director at the Center for Strategic and International Studies.

The Chinese spy balloon spotted this week could contain a camera, or a device used to capture electronic signals such as cell phone traffic, Karako said.

Besides cost, another advantage spy balloons have over satellites is they can hover over a specific point longer than the orbital pass of a satellite. Orbital passes can be tracked by adversaries, and the U.S. or another country could schedule around satellite monitoring, Byron Callan, Capital Alpha Partners managing director, said in a client note Friday morning.

Cause for concern

High-altitude balloons can also more easily pose as civilian in nature. For example, if a Chinese military drone was flying over U.S. airspace, it is obvious the government sent the aircraft.

With a spy balloon, foreign governments can claim it is used for a civil purpose, such as monitoring weather patterns. Beijing made that claim on Friday, saying the airship was being used for meteorological pursuits.

Over the past few years, spy balloons have flown over the continental U.S. a “handful” of times, a Defense Department official said on Thursday. But the distinguishing factor of the Chinese high-altitude balloon compared to other instances is the inflatable was “hanging out” for a longer period, said the official, who asked not to be named in order to discuss sensitive issues.

The high-altitude balloon was tracked flying over Malmstrom Air Force Base, home to silos containing intercontinental ballistic missiles.

“Clearly, they're trying to fly this balloon over sensitive sites,” the official said.

New uses

Using spy balloons dates to the late 1700s during the French revolutionary wars. The Union also flew them in the 1860s during the U.S. civil war to gather information about Confederate activity.

NASA began flying helium-filled stratospheric balloons in the 1950s, and the Army in the mid-2010s experimented with them at lower altitudes.

The service invested in a spy blimp program that it canceled in 2017. The effort is known as the Joint Land Attack Cruise Missile Elevated Netted Sensor System, or JLENS.

Unlike high-altitude balloons, the blimp was tethered and was designed to track boats, ground vehicles, drones and cruise missiles. One of the blimps broke loose over Maryland in 2015 and had to be brought down.

In 2019, the Pentagon worked on a project called the Covert Long-Dwell Stratospheric Architecture, designed to locate drug traffickers. At the time, the Pentagon launched 25 surveillance balloons from South Dakota as part of a demonstration.

The Pentagon confirmed to POLITICO last year that the project has transitioned to the military, but would not disclose details because the effort is classified. The airships could eventually be used to track hypersonic weapons from Russia and China.