Photo taken on May 28, 2021 shows the US Capitol building behind a traffic sign in Washington, DC, the United States. (PHOTO / XINHUA)

WASHINGTON — The United States has been using what can accurately be called "spy balloons" for decades, Fox News has said.

During World War I, the Goodyear Aerospace Corporation used its Akron air dock to build dirigibles to carry military payloads. More recently, the same air dock was used by Lockheed Martin to develop smaller balloons called aerostats, which can carry radar, infrared cameras, and more as their payload, said the report on Tuesday.

The report also mentioned that in 2015, Lockheed Martin tested a smaller "spy balloon" in Akron, Ohio, the payload of which was kept a secret

Many of these lighter-than-air "spy" craft were used along the US borders to detect drug smugglers flying into clandestine airstrips in the country, the report quoted Joseph Huber, who worked as a part of the team, as saying.

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The report also mentioned that in 2015, Lockheed Martin tested a smaller "spy balloon" in Akron, Ohio, the payload of which was kept a secret.

Huber said the smaller versions of the Aerostat were used by the military in the Middle East to watch enemy combatants, a surveillance program called the Persistent Threat Detection System.

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"They would stay up for several days at a time, bring them down quickly and refurbish and send them back up again, watching people coming in and putting explosives in the road and people trying to come in and make an attack on the base," Huber added.