Even before Mr. Snowden walked out of the Hawaii facilities of the N.S.A. with a trove of documents, it was clear that the United States was not above economic espionage, as long as it was not for the direct benefit of specific companies.

For example, the United States spies regularly for economic advantage when the goal is to support trade talks; when the Clinton administration was locked in a high-stakes negotiation in the 1990s to reach an accord with Japan, it bugged the Japanese negotiator’s limousine. At the time, the chief beneficiaries would have been the Big Three auto companies and a smattering of parts suppliers. It is also widely believed to be using intelligence in support of trade negotiations underway with European and Asian trading partners. But in the view of a succession of Democratic and Republican administrations, that is fair game.

Companies can also be targets. Documents released by Mr. Snowden showed that the American government pried deep into the servers of Huawei, one of China’s most successful Internet and communications companies. The documents made clear that the N.S.A. was seeking to learn whether the company was a front for the People’s Liberation Army and whether it was interested in spying on American firms. But there was a second purpose: to get inside Huawei’s systems and use them to spy on countries that buy the company’s equipment.

Huawei officials said they failed to understand how that differed meaningfully from what the United States has accused the Chinese of doing.

But such reasoning is rejected by the intelligence community. “I welcome this indictment because it has our government rejecting the false equivalence between us and the Chinese,” said Michael V. Hayden, a former director of both the N.S.A. and the Central Intelligence Agency. “It’s a risky course of action,” he added, “but prior to this we were in stasis.”

It is risky because the Chinese have already declared that they are shutting down, at least for now, the modest talks between the two countries on norms of behavior on the Internet.

Those conversations were already fraught. Last month, Defense Secretary Chuck Hagel went to Beijing to argue for a new channel of communication between the United States and China on cyberstrategy. American officials had already given the Chinese an overview of American cybersecurity, emphasizing that the N.S.A. did not take what it collects and hand it to Apple or Microsoft or Google.