The U.S. National Security Agency is reportedly collecting millions of Verizon (VZ) phone records after the government obtained a top-secret court order requiring the carrier hand over call data on all phone calls in its systems.

The White House on Thursday didn’t back away from the report in the U.K.’s Guardian, with a senior Obama administration official defending the practice in general terms.

Such information “has been a critical tool in protecting the nation from terrorist threats” because “it allows counterterrorism personnel to discover whether known or suspected terrorists have been in contact with other persons who may be engaged in terrorist activities, particularly people located inside the United States,” a senior official told Fox News.

New York-based Verizon declined to comment on the report, which indicated the company is expressly barred from disclosing to the public the existence of the request or the court order itself.

"Verizon continually takes steps to safeguard its customers’ privacy," Randy Milch, executive vice president of public policy and general counsel of Verizon, said in a memo to employees on Thursday.

However, Milch pointed out that the law "authorizes the federal courts to order a company to provide information in certain circumstances, and if Verizon were to receive such an order, we would be required to comply." 

The data Verizon has been ordered to hand over includes the phone numbers of both parties, location data and the time and duration of each call, the Guardian reported.

However, the report indicated the content of the calls is not included, meaning the government isn't able to actually listen in on the conversations through this order.

The administration official said the information does not include “the content of any communications or the name of any subscriber” and “relates exclusively to metadata, such as a telephone number or the length of a call.”

The order was issued by the Foreign Intelligence Surveillance Court on April 25 under a provision of the Foreign Intelligence Surveillance Act, or FISA. The order, which is classified, gives the government unlimited authority to obtain data for a specified three-month period ending on July 19, the Guardian reported.

Ron Gula, who worked at the NSA in the mid-1990s conducting security assessments of government networks, said any time his work got near U.S. citizens “there was a lot of oversight. I had to go to our general counsel.”

“My, how times have changed,” said Gula, who is now CEO of Tenable Network Security.

It’s not clear if other wireless providers like AT&T (T) and Sprint (S) may be subject to similar FISA orders. Both AT&T and Sprint declined to comment on the matter.

It’s also not clear if the Verizon order was a one-off or part of a series of similar orders.

The revelation represents an expansion of policies under the Bush administration and is already sparking outrage from Americans concerned about the government using terrorist threats as an excuse to encroach on privacy.

"It is beyond Orwellian, and it provides further evidence of the extent to which basic democratic rights are being surrendered in secret to the demands of unaccountable intelligence agencies,” Jameel Jaffer, deputy legal director at the American Civil Liberties Union, wrote in a statement.

Gula stressed that the intelligence community is “really, really good” at segmentation, or the walling off of information within a larger organization.

“It’s not like they got this data from Verizon and all of a sudden everyone at the NSA can check your phone records. It’s probably going to be limited in” who has access to that data, said Gula.

Verizon Wireless is a joint venture between Verizon Communications and Vodafone (VOD).

Shares of Verizon Communications rose 0.77% to $48.67 Thursday morning, leaving them up 12.5% on the year.

Follow Matt Egan on Twitter @MattMEgan5