There are few people more qualified to talk about President Trump’s disclosure of classified information to the Russians than Paul Pillar. Pillar served in the CIA for 28 years, where he worked on counterterrorism and the Middle East. Today he’s a professor at Georgetown, where he studies the intelligence community and US foreign policy.

So on Monday night, I called up Pillar and asked for his thoughts about Trump’s intelligence disclosure.

He was not amused.

“This is a very serious breach,” he said. “It indicates utter disregard, or utter lack of knowledge, at the very top!”

US intelligence-gathering efforts, especially when it comes to terrorism, rely pretty fundamentally on cooperation with foreign intelligence services. They have access to knowledge, by virtue of their geographic location and language skills, that US agencies simply don’t. Some of them may even have their own spies inside terrorist groups.

So when they share a critical piece of intelligence with the United States, they do so with the explicit understanding that the US will not share that information with anyone else unless they say it’s okay. That’s because doing so could potentially endanger the lives of their spies out in the field.

A major disclosure like this, on ISIS specifically, will make countries the world over less likely to cooperate with America — hampering the US’s ability to manage the ISIS threat at a time when intelligence is becoming all the more valuable in the ISIS fight.

What follows is a transcript of my conversation with Pillar explaining why, lightly edited for length and clarity.

Zack Beauchamp

What’s your reaction to all of this?

Paul Pillar

This is a serious breach of confidence with a liaison partner — that confidence being a critical part of intelligence-sharing relationships. I see that part of the White House spin after this incident is, “Well, he didn’t talk about intelligence sources and methods.” Well, if he had, that would have been an unbelievably egregious breach as opposed to a very concerning one.

Any use, at all, of information or reporting that came from a liaison partner that goes beyond use in our own government would be seen by the liaison partner as a serious breach of trust. And the cost for us, just on the intelligence level, is the likelihood that we won’t get similar information again — at least for a little while.

Zack Beauchamp

From this partner or many other partners?

Paul Pillar

Whoever this partner is. Although there would be a secondary effect, since this is in the news, among other partners about the unreliability — or at least the hazards involved — in sharing information with the United States, if any of that information gets to the White House.

I had personal experience when I was in the business. I recall one instance in which information that came from a particular partner was leaked. It wasn’t a matter of giving it directly to the Russian foreign minister — it was just a garden-variety Washington leak, and it wound up in the papers.

This partner cut off the sharing relationship for a while. When enough time went by, I had a meeting with their service. Part of my job was to be as profusely apologetic as I could about how the leak had occurred, and to offer as many assurances as I could that this won’t happen again, and could we please resume our exchange of information?

So at the intelligence level, this is a very serious breach.

Zack Beauchamp

There are sort of two strains to what you just said. The first is that breaches of foreign intelligence happen, and that intelligence services have means of dealing with it — though it’s unpleasant for a time.

But second, this isn’t just an ordinary leak to the media. This is the president literally telling the Russian foreign minister in a meeting.

Paul Pillar

Right.

Zack Beauchamp

So how would you rate this on a scale of “conventional” to “awful and unprecedented”?

Paul Pillar

I would consider this more serious. It indicates utter disregard, or utter lack of knowledge, at the very top!

So the foreign partners will say, “My goodness, even if we’re given assurances of how carefully our information will be used — as long we’ve got this guy at the top who does this sort of thing, those US assurances don’t mean very much.”

Zack Beauchamp

So how critically does US foreign intelligence depend on foreign cooperation?

Paul Pillar

It matters a great deal.

We’d like to think that our services, whether it’s intelligence services or anything else, are the best in the world. That we’ve got the technology and the smarts. But it’s at least as much a matter of access, experience, knowledge of the local neighborhood and the local culture and the local languages that is critical in collecting the sources of information we need.

Very often, there’s somebody else who’s better at those things than we are.

I would note that the topic involved is terrorism — and that was something I was deeply involved in. I would say, on terrorism, the reliance on foreign services sharing information is at least as important as any other intelligence topic.

That’s a reflection of the fact that these foreign internal security and intelligence and sometimes national police forces are on the front lines of confronting groups. As a matter of geography and language and culture, they are closer to the problem. So they’re better able to collect against groups than we are. Especially when we’re talking about human intelligence: A well-placed human source is the best possible source you can have on this.

Zack Beauchamp

It’s kind of a painful time too, right? These leaks were about ISIS. Right now the conventional war against ISIS is winding down as they lose territory in Iraq and Syria — and turning into a fight against harder-to-find but still dangerous ISIS cells.

Paul Pillar

As long as we’ve had this ISIS mini state, then as an intelligence target it’s had a lot of the same characteristics as a real state. You can use overhead imagery; you can go after this intelligence target in the way you go after big governments with return addresses.

In many ways, it’s still not as great a challenge as the tremendous challenge that’s faced in counterterrorism: going after plots and plans and infrastructure that consists of small, clandestine, highly secured groups of individuals. So yeah, I agree.

Zack Beauchamp

Shifting gears a bit: How do you think this will affect the president’s already rocky relationship with the intelligence community?

Paul Pillar

There are going to be buildings full of rolled eyes and expressions of exasperation.

I think there will be additional hard thoughts — I expect there were already a lot of these thoughts — about just what and how information can be presented to the White House, and specifically to the president. You can’t cut the president out ... the president is assumed to have every clearance there is.

Nonetheless, given that this particular president doesn’t seem to have much of an appetite for a large volume of information anyway, I think there’s going to be thoughts about restricting the flow even more. Then you immediately run into questions of, well, how do you do this with the president?

That’s one set of thoughts. There will certainly be conversations — if there haven’t been already — between senior intelligence officials and the likes of [National Security Adviser] Gen. [H.R.] McMaster to discuss this as a problem. And I’m sure McMaster, even though he said the requisite things trying to downplay this publicly, realizes this was a big problem.

Zack Beauchamp

That’s the thing that gets me, thinking about this. The whole system is dependent on the president signing off on things and the president having information on things.

You said earlier that you can’t cut the president off from sensitive information — and that’s really true. For him to make even minimally informed decisions, you have to tell him some really sensitive stuff.

Paul Pillar

It’s senior people at the White House — like the national security adviser — who play a critical role here. I can imagine some really sensitive stuff coming up where [Director of National Intelligence Dan] Coats or [CIA Director Mike] Pompeo comes to McMaster and says, “Tell us how we can work with you to handle this in a way that things don’t get screwed up when the boss is finally involved.”

Here’s maybe the plus side of Trump’s weaknesses. Given how much he seems to be hands-off with regards to national security stuff — we’ve seen all the reporting about how all kinds of authority has been delegated to [Secretary of Defense James] Mattis on things — well, from the intelligence community’s point of view, that’s maybe a good thing.

Zack Beauchamp

That’s kind of a grim upside, since it comes from the president’s ignorance.

Paul Pillar

That’s exactly what I’m saying, yes.

The great debate is: Is the incompetence of this administration something we should be happy about, so they can’t do all the authoritarian awful things they would do if they were more competent? It’s kind of finding another negative to offset the first negative.