Huawei officials argued that the latest charges were not new allegations and appeared to be part of a larger campaign against the company. It is confident that it will be exonerated in the criminal justice system, said Andy Purdy, the chief security officer for Huawei in the United States.

He said the U.S. government was trying to hurt Huawei by pressuring allies not to use its equipment and was attempting to block American companies from selling parts to the Chinese firm. Both campaigns will ultimately hurt America, Mr. Purdy said, by eliminating jobs in the United States and reducing competition in the telecommunications industry.

He said the U.S. government was engaged in a “campaign to carpet bomb Huawei out of existence,” adding: “It seems like the United States is not thinking about the significance of this.”

The indictment portrays Huawei as orchestrating a steady, if not sophisticated, campaign to steal trade secrets. For instance, the indictment alleged that in 2004, a Huawei employee sneaked back to a Chicago trade show to steal a competitor’s technology.

The employee “was discovered in the middle of the night after the show had closed for the day in the booth of a technology company” and was found “removing the cover from a networking device and taking photographs of the circuitry inside.” The individual wore a badge listing his employer as “Weihua” — an anagram of Huawei — according to the indictment.

In another episode, prosecutors say, Huawei planned “countermeasures” against a company making data storage technology. It invited leaders of the firm to make a presentation about its plans, then asked for a copy of the slides used in the presentation and “immediately” shared it with engineers at its subsidiary working on a competing product, according to the indictment.

Huawei has had legal disputes with several of the companies it is accused of stealing from. Cisco, a computer networking equipment maker in San Jose, Calif., sued Huawei in 2003, claiming the Chinese company infringed on numerous patents and illegally copied its software source code and documentation. The suit was dropped about a year later in exchange for a promise of product changes from Huawei.