WASHINGTON: President Barack Obama's orders to change some US surveillance practices put the burden on Congress to deal with a national security controversy that has alarmed Americans and outraged foreign allies. Yet he avoided major action on the practice of sweeping up billions of phone, email and text messages from across the globe.

In a speech at the Justice Department on Friday, Obama said he was placing new limits on the way intelligence officials access phone records from hundreds of millions of Americans - and was moving toward eventually stripping the massive data collection from the government's hands.

His promises to end government storage of its collection of data on Americans' telephone calls - and require judicial review to examine the data - were met with skepticism from privacy advocates and some lawmakers.

But Obama has made it nearly impossible for reluctant leaders in Congress to avoid making some changes in the US phone surveillance they have supported for years.

Obama admitted that he has been torn between how to protect privacy rights and how to protect the US from terror attacks - what officials have called the main purpose of the spy programs.

"The challenge is getting the details right, and that is not simple," he said.

His speech had been anticipated since former National Security Agency analyst Edward Snowden made off with an estimated 1.7 million documents related to surveillance and other NSA operations and gave them to several journalists around the world. The revelations in the documents touched off a public debate about whether Americans wanted to give up some privacy in exchange for intelligence-gathering on terror suspects.

The president said his proposals "should give the American people greater confidence that their rights are being protected, even as our intelligence and law enforcement agencies maintain the tools they need to keep us safe."

Obama acknowledged more needs to be done, but he largely left it to Congress to work out the details.

The NSA says it does not listen in on the phone calls or read the Internet messages without specific court orders on a case-by-case basis. But intelligence officials do collect specific information about the calls and messages, such as how long they lasted, to try to track communications of suspected terrorists.

Plans to end the sweep of phone records have been building momentum in Congress among both liberal Democrats and conservative Republicans. Congressional leadership and the chairmen of the intelligence committees who for years have signed off on the programs have opposed dramatic changes.

Obama's order signals that the phone program must be overhauled, and lawmakers called his speech a welcome first step.

"It is now time for Congress to take the next step by enacting legislation to appropriately limit these programs," said Rep. Bobby Scott, D-Va., a member of the House Judiciary Committee.

The leaders of the Senate and House intelligence committees, which have proposed far less sweeping legislation, threw the responsibility back to Obama.

"We encourage the White House to send legislation with the president's proposed changes to Congress so they can be fully debated," Sen. Dianne Feinstein, D-Calif., and Rep. Mike Rogers, R-Mich., said in a coolly worded statement.

Privacy advocates called Obama's proposal a shell game - by assigning the collection to a new, as-of-yet undecided entity instead of ending it outright. They had even sharper criticism for the speech's scant attention to the NSA program that intercepts billions of overseas Internet messages and phone conversations from foreigners each day.

The program, authorized under Section 702 of the Foreign Intelligence Surveillance Act, allows the US government to read or listen to the messages and phone calls as long as they do not target American citizens who live overseas.

Obama said he would seek new restrictions on the government's ability to collect or use the overseas messages that accidentally included messages or phone calls from Americans. But he did not spell out how, or by when.

Nor did Obama specify any sweeping changes to the so-called 702 program to protect foreigners' privacy, although he did broadly promise to order "the unprecedented step of extending certain protections that we have for the American people to people overseas." He said that would include limiting the time that the US holds the foreign information it collects and restricting its use.

Given the mass of the foreign communications surveillance, the reforms offered Friday offered just a "sliver" of respite from fears of US spying, said Matt Simons, director of social and economic justice at Chicago-based software company ThoughtWorks.

"There was a clear attempt to narrow down what we're talking about to the easiest, lowest-hanging fruit," said Simons, whose company is among a number of US tech firms demanding broad reforms to prevent their clients from defecting to foreign firms that might offer more protections.

Mark Jaycox, legislative analyst at the Electronic Frontier Foundation in San Francisco, predicted that the foreign surveillance under Section 702 will be Congress' next target after the government stops storing its collection of Americans' phone records. The group is suing the NSA to reveal more information about the programs.

At a Brookings Institution forum Friday afternoon, intelligence experts debated the effects of Obama's orders on privacy, security and commerce. While the collection of Americans' phone records "is the molten core of the political debate," the surveillance of foreigners' communications is at the heart of NSA operations, senior fellow Benjamin Wittes said.

Massive changes likely would not be needed, Wittes said, because US intelligence officials generally don't eavesdrop on or read foreign communications they don't need. He called Obama's pledge to protect foreigners' privacy rights a significant step toward rebuilding US trust overseas.

"It is very hard to overstate the sort of spiritual importance of that statement," Wittes said. "This might be an area where the spiritual statement goes a long way without actually changing very much."