In an interview with National Public Radio, the deputy director of the National Security Agency Richard Ledgett claimed the NSA has lost track of about 1,000 intelligence targets since 2013 because of NSA leak Edward Snowden’s revelations, including a terrorist group that was planning attacks against the United States and Europe.

The good news, in the deputy director’s estimation, is that much of the information disclosed by Snowden is becoming obsolete. “The amount that matters from a technical capabilities sense has decreased over time,” he told NPR.

Then came the bad news: About a thousand of the NSA’s intel targets are taking “steps to remove themselves from our visibility,” using Snowden’s dangerously extensive disclosures about how that visibility worked.

“There was a terrorist group that was actually engaged in operational planning directly against the United States and western Europe, that changed the way they communicated because of those disclosures. And they said they were going to do it, and they did it, and we lost track of them,” said Ledgett, without disclosing any further details, other than a time frame of about 18 months ago.

It is a grim testimony to the level of terrorist activity that knowing the time frame does not help much when trying to guess which terror attack he is talking about. Snowden defenders usually claim that such vague assertions mean the intelligence community is lying or exaggerating to paint the defector in a more negative light.

Snowden himself recently repeated his assertion that the NSA programs he exposed provide very little benefit to the war against terrorism. “It was diplomatic manipulation, economic spying and social control. It was about power, and there is no doubt that mass surveillance increases the power of the government,” he said in an interview with Spanish television, as reported earlier this week by Russian propaganda outlet RT.com.

In his NPR interview, Ledgett pronounced himself satisfied with the new programs implemented after the Snowden revelations, particularly the way private companies are now storing bulk communications data instead of the NSA, although he noted the new approach has been somewhat slower and more expensive thus far.

He anticipated the speed concerns would be addressed by the new “NSA 21” reorganization plan, which would make the agency “more agile about how we prioritize, how we pivot from one topic to another.”