Brazil plans to divorce itself from the US-centric internet over Washington’s widespread online spying, a move that many experts fear will be a potentially dangerous first step toward politically fracturing a global network built with minimal interference by governments.

President Dilma Rousseff has ordered a series of measures aimed at greater Brazilian online independence and security following revelations that the US National Security Agency intercepted her communications, hacked into the state-owned Petrobras oil company’s network and spied on Brazilians who entrusted their personal data to US tech companies such as Facebook and Google.

“The global backlash is only beginning and will get far more severe in coming months,” said Sascha Meinrath, director of the Open Technology Institute at the Washington-based New America Foundation think-tank. “This notion of national privacy sovereignty is going to be an increasingly salient issue around the globe.”

While Brazil isn’t proposing to bar its citizens from US-based Web services, it wants their data to be stored locally as the nation assumes greater control over Brazilians’ internet use to protect them from NSA snooping.

Ms. Rousseff says she intends to push for new international rules on privacy and security in hardware and software during the UN General Assembly meeting later this month.

Most of Brazil’s global internet traffic passes through the United States, so Ms. Rousseff’s government plans to lay underwater fibber optic cable directly to Europe and also link to all South American nations to create what it hopes will be a network free of US eavesdropping.

Ms. Rousseff is urging Brazil’s Congress to compel Facebook, Google and other US companies to store all data generated by Brazilians on servers physically located inside Brazil in order to shield it from the NSA.

If that happens, and other nations follow suit, Silicon Valley’s bottom line could be hit by lost business and higher operating costs.

Brazil also plans to build more internet exchange points, places where vast amounts of data are relayed, in order to route Brazilians’ traffic away from potential interception.

International spies, not just from the United States, also will adjust, experts said. Laying cable to Europe won’t make Brazil safer, they say. The NSA has reportedly tapped into undersea telecoms cables for decades.

Mr. Meinrath and others argue that what’s needed instead are strong international laws that hold nations accountable for guaranteeing online privacy.

“There’s nothing viable that Brazil can really do to protect its citizenry without changing what the US is doing,” he said.