The surveillance cameras and other equipment that Aventura Technologies sold for years to the United States military looked like solid American products, packaged in boxes with “Made in the U.S.A.” labels and stars-and-stripes logos.

The items were installed throughout government agencies, including on aircraft carriers and a Department of Energy facility. Then last year, a service member on an Air Force base noticed that an Aventura body camera displayed Chinese characters on the screen.

On Thursday, federal prosecutors in Brooklyn said that the equipment had actually been made in China and was vulnerable to hacking, raising the possibility that American government agencies had installed software in their security networks that could be used for spying by China.