Keith Alexander insists pilot programs were not used for analysis but that tracking location data 'may be a future requirement'

The head of the National Security Agency has admitted to secret pilot programs to monitor the precise location of Americans through their cellphones, saying the highly intrusive tracking data "may be something that is a future requirement for the country".

General Keith Alexander, the director of the NSA, said that the pilot programs from 2010 and 2011 were intended to test the compatibility of the location data with the agency's databases, but were not used for any intelligence analysis purposes.

However, giving evidence to the Senate judiciary committee on Wednesday, Alexander left little doubt that the NSA was interested in a potential dragnet of location data, which would constitute a significant extension of its surveillance powers.

Last week, before another Senate committee, Alexander evaded questions about whether the NSA had ever collected information from cellphone towers, which helps pinpoint an individual's movement, suggesting the information might be classified.

Asked on Wednesday by Republican senator Ted Cruz whether the NSA would ever seek location data of Americans to combat terrorism, Alexander said that would be a possibility, but that the agency currently obtains the information on a case-by-case basis.

"I would just say that this may be something that is a future requirement for the country, but it is not right now, because when we identify a number, we can give that to the FBI," Alexander said. "When they get their probable cause [to justify obtaining the data] they can get the location data that they need."

"The NSA's attempt to collect this data shows the need for stronger legislative oversight of the agency's activities, but the fact is that federal, state, and local law enforcement are already regularly collecting cell phone location information without a warrant," said Christopher Calabrese, ACLU legislative counsel. "Last year a majority of the supreme court recognized that location information is sensitive, and we need legislation that respects privacy rights when it comes to Americans' movements."

After the hearing, the ACLU objected to the phone-tracking revelation. "The NSA's attempt to collect this data shows the need for stronger legislative oversight of the agency's activities, but the fact is that federal, state, and local law enforcement are already regularly collecting cell phone location information without a warrant," said Christopher Calabrese, ACLU legislative counsel.

"Last year a majority of the Supreme Court recognized that location information is sensitive, and we need legislation that respects privacy rights when it comes to Americans' movements."

In another exchange, Alexander and James Clapper, the director of national intelligence, appealed to Congress not to allow the string of disclosures based on documents provided by whistleblower Edward Snowden to limit the powers of the intelligence community.

Both men criticised some media reports, which they said were misleading and dangerous to national security. However, in a series of revealing exchanges, they were themselves accused of misleading the public and forced to shed light on the pilot programme to obtain cellphone data, as well as another effort to collect huge amounts of social network data on foreign citizens.

Patrick Leahy, the chairman of the committee, also criticised the information had that been provided to a privileged few lawmakers.

"We get more in the newspapers than we do in the classified briefings that you give us," Leahy said.

Leahy, a Democrat who is drafting legislation to reform US government surveillance, pressed Alexander and Clapper on the accuracy of their previous testimony.

"Both of you have raised concerns that the media reports about the government's surveillance programs have been incomplete, inaccurate, misleading," Leahy said. "But I worry that we're still getting inaccurate and incomplete statements from the administration."

He drew attention to repeated claims by the intelligence agencies that 54 terrorist attacks had been thwarted by two particular programs.

"That is plainly wrong, but we still get it in letters to members of Congress, [and] we get it in statements," Leahy said. "These weren't all plots, and they weren't all thwarted. The American people are getting left with inaccurate reflection of the NSA's programs."

Alexander then conceded that the 54 examples were "not all plots" and only 13 had a nexus in the US. He also admitted there were only "one or possibly two" cases of terrorist activity that would not have been prevented "but for" section 215 of the Patriot Act, which authorises bulk phone record collection.

The majority of reports based on Snowden's disclosures have been published in the Guardian, including the first disclosure, in June, that the NSA was secretly feeding a huge database of the records of phone calls of millions of Americans.

Since then, a number of other media outlets have published reports based on some top-secret documents disclosed by Snowden, including, most recently, the New York Times. It reported over the weekend that the NSA has been exploiting its huge collections of data to create sophisticated graphs of some Americans' social connections, for foreign intelligence purposes.

Alexander said the report, based upon an internal NSA memo from January 2011, that lifted previous restrictions on "discover and track" connections between foreign intelligence targets and people in the United States, were "inaccurate and wrong".

Asked if he was collecting data to build portraits of social networks, Alexander replied: "No."

However, Alexander then appeared to row back on that position, stressing that the NSA was obtaining supplementary information, under executive order 12333, to connect data they already have "to social networks abroad".

He said the order, which would not be subject to oversight mechanisms that apply to other programs, was still operating.

Earlier, Leahy spoke about the bill he is drafting to limit the intelligence agencies surveillance reach in partnership with Republican Jim Sensenbrenner, who chairs the crime and terrorism subcommittee of the House of Representatives.

Their legislation, which is still being drafted, would end the bulk collection of phone records under section 215 of the Patriot Act, introduce a special advocate to the foreign intelligence surveillance act (Fisa) court – along with some measures to make the court more transparent. The Leahy-Sensenbrenner legislation has a good chance of rising above the dozen or so other bills being proposed in the aftermath of the Snowden disclosures.

Leahy and Sensenbrenner are heavyweight politicians from opposite sides of the political spectrum. After the September 11 attacks, Sensenbrenner introduced the Patriot Act, a law he now says was misinterpreted by spy agencies and used to justify surveillance programs that infringe on constitutional rights.

"Just because something is technologically possible, and just because something may be deemed technically legal, does not mean it is the right thing to do," Leahy said.

"The government has not made the case that at the bulk collection of phone records is an effective tool," he added.

Leahy said he had reviewed the classified case the intelligence community makes for the phone collection program, "and I find it to be unconvincing".

Senator Chuck Grassley, the ranking Republican on the committee, said that recent revelations that NSA staff had used the agency's powerful surveillance tools to spy on their spouses had fed into a "broader crisis of trust" that the intelligence establishment would struggle to recover from.

Alexander assured the committee that most of the violations of NSA rules related to "foreign persons in foreign places".

In opening statements, Clapper and Alexander echoed almost word for word the evidence they provided the Senate intelligence committee last week, arguing that media outlets have endangered national security by publishing Snowden's disclosures, and claiming that intelligence agencies are not interested in spying on US citizens.

In a written submission to the committee, the pair reiterated the position of the intelligence establishment: that while they will consider some minor changes to the way they do business to increase public confidence in the wake of the Snowden disclosures, they will not countenance any significant diminution of their powers, which they believe are vital for national security.