It's a proper use of "intellectual property", but they're not talking about movies and books.

Intellectual property is something whose use is protected by law. (In particular, the fact that you have to break the law to obtain the information does not make it intellectual property.) These are just secrets, right?

Most things stolen in industrial espionage are either copyrighted or trade secrets, both of which fit within a formal definition of intellectual property.

No. If I designed an unmanned airplane, would the blueprints, source code, and specs be considered IP? You betcha.

By intellectual property I'm sure they mean products of R&D or things reminiscent of that.

It think it's just being used in contrast to physical property. But it is a little weird.