The new director of the National Security Agency on Tuesday acknowledged that the agency uses facial-recognition tools but said the intent is primarily to identify terrorists and help prevent attacks — adding that such technologies are not broadly directed against Americans.

“We do not do this on some unilateral basis against U.S. citizens,” said Adm. Michael S. Rogers, in some of his first public remarks since taking the helm of the embattled spy agency two months ago.

A year after the first leaks emerged about the scope of NSA surveillance programs, Rogers is seeking to reframe the public debate that has damaged the reputation and morale of the NSA, saying the public needs to understand not just what the organization does but also why it does it and under what limits.

Speaking at a Bloomberg cybersecurity conference, Rogers said the agency does not have access to drivers’ licenses or passport photo databases to search for Americans. The New York Times reported Sunday that the agency harvests about 55,000 “facial recognition quality images” on a daily basis as part of its global surveillance operations.

“Our mission at the NSA is very explicit — foreign intelligence and [cybersecurity],” he said. “If we do anything against U.S. persons, we have specific legal constraints that we must apply. We just don’t unilaterally decide, ‘Hey, today I’m going after Citizen X, Y and Z.’ ”

Leaks by former NSA contractor Edward Snowden have revealed, for instance, that the agency has been collecting and recording an entire foreign nation’s phone calls and has tracked large numbers of cellphone locations overseas for foreign intelligence purposes.

Rogers argued that the public has not focused on the protections afforded Americans in its collection efforts. “If we come to a realization that someone we’re tracking has a U.S. connection that we were unaware of, in broad terms, we have to stop what we’re doing,” he said. “If we think there’s a legal basis to this, then we have to get a legal authority or justification” to continue.

But he did not address what happens with the communications of Americans who are not targeted but whose data is swept up anyway, either because they are in contact with a target or because of the way data is collected. How much of that data is being collected today, how often that data is searched for Americans’ communications, and how strong the protections ought to be are still matters of debate.

This is particularly an issue in an era in which digital communications zip around the globe, defying the distinctions created by a privacy system that places greater restrictions on data intercepted on U.S. soil.

Rogers also sought to broaden public concern beyond what the spy agency is doing to the vast amounts of digital data being collected through other means or by private companies — “whether it’s the cameras out on the street or every one of your personal digital devices constantly asking you, ‘Can I share where you are?’ ”

He added: “We have framed this debate way too narrow, from my perspective. This is much bigger than the National Security Agency.”

Rogers did not, however, discuss the deeper questions of why it is in the nation’s interest for the agency to collect such large amounts of digital data and whether pervasive surveillance will diminish user trust in the Internet.

Asked his opinion of Snowden, who was recently interviewed by NBC News, Rogers said he seemed to be “an intelligent individual, articulate.” But, he added: “He seemed fairly arrogant . . . I fundamentally disagree with what he did.”

Asked whether he thought that Snowden, who is in Russia under temporary asylum, could be a double agent, Rogers said: “Probably not.” But, he added, an investigation continues.