This is a rush transcript from "On the Record," June 14, 2012. This copy may not be in its final form and may be updated.

GRETA VAN SUSTEREN, FOX NEWS HOST: Tonight, former defense secretary Donald Rumsfeld. What does he think about the dangerous leaks of top secret information? Who does he think is the source? Is it the White House?

Here is Secretary Rumsfeld.

(BEGIN VIDEOTAPE)

VAN SUSTEREN: Mr. Secretary, nice to see you, sir.

DONALD RUMSFELD, FORMER DEFENSE SECRETARY: Thank you, Greta.

VAN SUSTEREN: First the question of the leaks. I'm curious, your evaluation of these leaks, how serious they are.

RUMSFELD: I think quite serious. And the problem is you'll never know how serious for some time because we -- our country goes out to other countries and asks them to cooperate with our intelligence services. And when they see a behavior pattern, where we are not responsible and don't behave properly with respect to important information that they give us, they're going to not want to cooperate with us.

And if you have countries backing away, unwilling to cooperate, America loses and the American people lose. The same thing with individuals. We go to individuals and ask them to cooperate with us. And if they're compromised and their families are put at risk and they're put at risk, it tells everyone else we ask to help us, Be careful of America. And so it's a serious problem.

VAN SUSTEREN: In some ways, that's sort of the big picture view of this. In this -- one of -- one of the leaks is about this cyber-attack on Iran's nuclear facilities. And it seems to me that that is even more dangerous because we've heard so much about Israel can't go alone against Iran to knock out their nuclear weapons program. And we've been going back and forth, to some extent, to what we're involved and what we're going to do.

This was sort of, it seemed like, a really quick potential way to disable it. And so this one seems to have a real direct impact on Israel, who had developed this cyber-worm with us.

RUMSFELD: You know, I'm not into the details. But there's no question but that countries are vulnerable to cyber-attacks, including the United States. And how they're done and who does them is not something that ought to -- in my view, ought to be discussed in the public.

VAN SUSTEREN: How -- well, let me ask you this question. How safe are we from a reverse situation? Do you have any sort of sense of that, how safe we are from a cyber-attack from another country?

RUMSFELD: I think it is probably correct to say that the countries that are the most advanced technologically, the United States, and the countries that are the freest and pride themselves on being free nations and people being free are the most vulnerable.

And if you think of the extent to which we've thrown away the shoeboxes with the three-by-five cards or the old IBM cards with the punches in them and are dependent on digits -- everything's dependent on digits today, and there's our vulnerability. And it's real and serious.

VAN SUSTEREN: Is the vulnerability of -- I mean, I don't mean to understate this, but it can disrupt our financial system...

RUMSFELD: Electric grid.

VAN SUSTEREN: Electric grid. I mean, give me some idea how bad it could be. I mean, it's, like -- I mean, I don't -- I don't want to get sort of -- be an alarmist, but I'm trying to think, like, is it something that we could -- that's just going to be disruptive for two months and we're all going to be, you know, very distressed and disturbed, or is it much more cataclysmic than that?

RUMSFELD: Well, it's much more serious. I mean, just take Katrina. Once electricity goes out, you can't lift (ph) gas. You can't get gas out of a gas station. It doesn't pump. People can't move around. You can't rescue people.

The potential is to disable an activity like a power grid. The potential is to confuse and mislead. And the potential is to deny capability. So it runs the full gamut of -- cyber-attacks can run the full gamut, and in every respect, technologically advanced countries, countries that are more heavily dependent on digits than most, people that are more - - banks and people that are more heavily dependent on digits are the most vulnerable.

VAN SUSTEREN: How do we know -- and I guess an investigation will give us a little information, but that'll be some time down the road -- whether this particular leak, about these three -- the three topics that are leaked that everyone has seized upon, which is the double agent and -- and one -- and the cyber-attack, and of course, the kill list -- how do we know, or how do we assess whether this was a clumsy, incompetent leak, or whether this was sort of a deliberate, with some sort of sinister motive, for instance, a political motive?

RUMSFELD: Everything I can tell watching it, as an observer of these things, is that it did not come from the Department of Defense and did not come from the CIA. And indeed, if I were at the Department of Defense -- and I suspect the military over there, whose people are put at risk when there's additional information learned about how we conduct our operations -- have to be grinding their teeth.

It looks to be out of the White House. Now, at what level in the White House, I'm not in a position to know.

VAN SUSTEREN: But is it out of the White House that someone said someone to somebody else who said something to somebody else, and shouldn't have said any of this stuff at all, or is it something where someone -- do we get a sense that it was done for a selfish political reason? Because that's very different. Both are bad. But one to me is much more sinister and troubling than the other, regardless of the -- they have the same impact.

RUMSFELD: Well, I just don't know. And if -- you know, if a disinterested observer looked at it, they'd have to say that it had the cumulative effect of advantaging the president politically.

VAN SUSTEREN: When people have these discussions, when you had them (INAUDIBLE) how many people are usually in the room? Any -- I mean, I assume it varies, but I mean, how -- how many would you assume at any given time on these very high-level classified meetings?

RUMSFELD: Well, you saw the picture of the -- taken in the Situation Room when they discussed the attack on bin Laden. That's about right. There are some military people. There are some political people. There are some CIA people. There's some civilians from the Department of Defense and some White House staff.

So you're looking -- in a Situation Room, you'd probably have around the table 6 or 7, and on the straphangers in the back, you'd probably have another 8. You're talking anywhere from 14 to 20.

VAN SUSTEREN: All right, so some of the discussion, though, inside the Situation Room isn't classified. Some of it, I assume, is non- classified.

RUMSFELD: Sure.

VAN SUSTEREN: Some of it -- I mean, how usually is it delineated so that people know for sure, Don't say this one? I mean, I assume it's not simply left up to good judgment. I assume that -- you know, that there's some sort of ability to determine that, This is classified, don't talk about it, you can talk about this?

RUMSFELD: Once the president calls a meeting in the Situation Room and you've got the National Security Council and then the deputies or the people behind, the people there don't need anyone to tell them what's sensitive or what's not sensitive.

If the president decides that something is particularly sensitive, or the director of CIA or the secretary of defense or the secretary of state, they then would have a principal-only meeting, and you would have the president, the vice president and the members of the National Security Council, the secretary of defense, secretary of state, CIA director and the chairman of the Joint Chiefs.

If there's something that is even -- needs to be even restricted to a greater extent, and the secretary of state or defense or CIA director decide that they have a piece of information that would be terribly damaging and compromise our troops or compromise an ally that provided us the information, something of an operational nature, they might very well simply talk to the president and not even do it in a meeting with others present.

So people who are around these things over the years, you know, have levels where they operate.

VAN SUSTEREN: Experience, in some way.

RUMSFELD: Sure.

VAN SUSTEREN: I mean, they -- they get it. All right, now, if something's classified, at some point it might become unnecessary to have it classified. Is it officially declassified by the president, or can it be sort of informally, saying, OK, we're not -- this is going to be -- this no longer classified?

RUMSFELD: Yes. It can be classified at one level, and that level can be reduced as time goes on, if there's a reason to do that and you want to include more people.