WASHINGTON, May 21  -- U.S. media revealed Wednesday the U.S. government routinely spies on foreign companies to seek economic advantage.

"The National Security Agency (NSA) has never said what it was seeking when it invaded the computers of Petrobras, Brazil's huge national oil company, but angry Brazilians have guesses: the company's troves of data on Brazil's offshore oil reserves, or perhaps its plans for allocating licenses for exploration to foreign companies," said an article published by the New York Times.

"Nor has the NSA said what it intended when it got deep into the computer systems of China Telecom, one of the largest providers of mobile phone and Internet services in Chinese cities," it said.

But documents released by Edward Snowden, the former agency contractor now in exile in Russia, leave little doubt the main goal was to learn about Chinese military units, whose members could not resist texting on commercial networks, it said.

The article said the agency's interest in Huawei, the giant Chinese maker of Internet switching equipment, and Pacnet, the Hong Kong-based operator of undersea fiber optic cables, was more obvious: Once inside those companies' proprietary technology, the NSA would have access to millions of daily conversations and emails that never touch American shores.

Then there was Joaquin Almunia, the antitrust commissioner of the European Commission. He ran no company, but had punished many, including Microsoft and Intel, and just reached a tentative accord with Google that would greatly change how it operated in Europe, it said.

American officials insist the United States was never acting on behalf of specific American companies, said the article. "But the government does not deny it routinely spies to advance American economic advantage, which is part of its broad definition of how it protects American national security."

In short, while the NSA could not spy on Airbus and give the results to Boeing, it was free to spy on European or Asian trade negotiators and use the results to help American trade officials - and, by extension, the American industries and workers they were trying to bolster, it said.

In the Chinese view, the article said, the United States had designed its own system of rules about what constituted "legal" spying and what was illegal.

"That definition, the Chinese contend, is intended to benefit an American economy built around the sanctity of intellectual property belonging to private firms," it said.

It was also designed to give the NSA the broadest possible rights to intercept phone calls or email messages of state-owned companies from China to Saudi Arabia, or even private firms that were involved in activities the United States considered vital to its national security, with no regard to local laws, the article said, adding the NSA said it observed American law around the globe, but admitted local laws were no obstacle to its operations.

The article also pointed out that state-run oil companies were a fascination for the NSA. State oil companies in Saudi Arabia, Africa, Iran and Mexico have often been intelligence targets for the United States.

"Petrobras is a case in point. In the American view, Brazilian energy policy is made inside the state-run company, which is indistinguishable from the government. Thus, under the same rationale that the United States intercepted the phone calls of the country's president, Dilma Rousseff, it had the authority, as a collector of foreign intelligence, to delve inside the company," it said.

Rousseff, denouncing the NSA at the United Nations last September, said the agency's activities amounted to "a breach of international law and an affront" to Brazil's sovereignty, according to the article.