Apple's senior executives are on a media blitz in celebration of the Mac's 30th birthday. Phil Schiller, Craig Federighi, and others spoke with Macworld yesterday, and today it's CEO Tim Cook's turn to face the press. Joined by Federighi and software VP Bud Tribble, he recently held an interview with ABC News at Apple's Cupertino campus. The interview will air in its entirety tonight on World News with Diane Sawyer, but early morning viewers were given a preview during Good Morning America. The below clip largely steers clear of the Macintosh — presumably we'll hear more on that during the evening segment. Instead, Cook fields questions on his own work ethic (he reads up to 800 customer emails each day), Apple's obsession with secrecy, manufacturing in America, and the fabled iWatch.

"I'm a workaholic."

"We believe fundamentally that people love surprises," Cook says. To try and maintain that element of surprise around its product roadmap, Cook confirms that at Apple's headquarters, upcoming devices and other works in progress are guarded by several layers of security. "There are black drapes and numerous locked doors and many other things." Cook also points out — as other executives have in the past — that Apple employees are often sworn to total secrecy and can't tell family members about projects they're working on. "My wife has no idea," says Federighi.

When asked about Apple's plans for manufacturing in the US, Cook describes the latest Mac Pro as "a big deal." (The powerful desktop is assembled in Austin, Texas.) But just as quickly, he admits that the company "can do more." Part of that commitment involves a brand new manufacturing facility in Arizona. Cook confirms that the plant will be used to produce sapphire glass, but offers no additional hints. When asked whether sapphire will be used as part of the display on a future iPhone, Cook answers flatly, "I can't tell you that." He also manages to avoid any serious discussion of the iWatch — at least in this preview. When the topic of wearables is brought up, Cook jokes that Apple is working on "a ring."

The most interesting part of the interview is likely to come later tonight. Addressing the NSA controversy, Cook reportedly says he could "put [the] American people at rest" if the government permitted him to discuss surveillance in greater detail. For that portion of the discussion, you'll need to wait for the full segment.

Update: The segment of tonight's interview dealing with the NSA has been released. "I’ve been pushing very, very hard to open the books and be totally transparent," says Cook when asked for his thoughts on surveillance. He then reiterates what Apple has said before. "There is no back door. The government doesn’t have access to our servers." Cook says, "They would have to cart us out in a box for that. And that just will not happen. We feel that strongly about it."

Cook is never asked directly about DROPOUTJEEP, a tool described in a 2008 NSA memo that allowed the agency to tap into iPhones. Apple has insisted it had no knowledge of DROPOUTJEEP before it was publicized as part of the Snowden leaks.

But it's clear Cook wishes he were in a position to share more details on what sort of information the government wants. "I do want to be transparent, because I think transparency would help put everything in perspective."