How did low-level employees access national secrets?

Whatever the motives of whistleblowers Edward Snowden and Bradley Manning, the obvious question that both these cases raise is how is it that an Army private and one of the guys on the National Security Agency's IT help desk could wind up with access to some of the nation's most closely guarded secrets?

After the 9/11 attacks were blamed on the government's failure to connect the dots, the CIA, FBI and other intelligence agencies were ordered to exchange more classified information.

It was all about stopping the next attack. But that also meant the secrets were shared with more people -- one of them Army private Bradley Manning.

"It frightened me when I was running counterintelligence because I predicted this kind of disaster," said Joel Brenner, who was the National Security Agency's top counterintelligence official. While he supports increased sharing, Brenner said too many people have too much access.

"The pressure to share everything after 9/11 was relentless," he said. "And it came from the Congress, it came from the White House, it came from the heads of agencies."

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"It was almost as if we were conducting foreign relations in Mister Rogers' neighborhood -- 'everyone should be nice and share anything,'" he continued.

More than 1.4 million people now hold top-secret clearances. About a third of those are government contractors.

Edward Snowden was one of them. And Snowden's case has revealed yet another security hole. As an IT specialist, Snowden had broad access to NSA programs and was able to download secret details with no direct supervision.

Now the government is implementing a "two-person rule." Systems administrators like Snowden will no longer work alone.

Brenner said that will help, but the nation's secrets will remain vulnerable.

"There will be more leaks," he said. "We can do a better job of reducing them but transparency has come to the intelligence business."

Officials say information sharing does work and has played a role in disrupting dozens of plots. But they also acknowledged the intelligence system is largely based on integrity and on the premise that those sworn to keep the nation's secrets will honor that oath.