Well, it's kind of inevitable given how interconnected the world is today. It was a lot simpler to distinguish between foreign and domestic 40, 30, even 20 years ago before cellphones were ubiquitous and when control of bandwidth was in far fewer hands - and even at that, the NSA still worked within the US monitoring things like communications between foreign embassies/consulates. Not only are global communications more intricate, but more people have personal foreign relations thanks to the affordability of travel and the globalization of communication, news, etc.
What's happening at the NSA has many analogues in the private sector and is to a large extent driven by technology.
What's happening at the NSA has many analogues in the private sector and is to a large extent driven by technology.