"There has been much speculation as to whether or not we destroyed some, if not all, of the North Korean missiles launched yesterday, in explicit violation of requests from all of the five parties in negotiation with it to not do so. In the interests of the security of the US and the region, we can neither confirm or deny such speculation."

Depends. With a stable, traditional and most importantly largely equal opponent, e.g. the USSR during the Cold War, I'd say it's better they know our general capabilities, because that helps prevent paranoid thinking that can lead to more-or-less unintentional war. It's a bit of a Heinleinesque situation ("an armed society is a polite society").

But with an unequal terroristic opponent, I think it's better if they don't know, so overconfidence makes them overreach and expose their capabilities and intentions before they're market-ready. Sort of like a special ops surveillance, where you want the target to feel so confident he gets careless.

Besides, I'd say what we actually want here is for the Nokos to continue to shoot off a missile every six months or so. Gives the MD people nice live-fire training and testing. Saves the US taxpayer the cost of launching our own targets. Keeps that segment of the voting public with the attention span of field mice more aware of the general problem, and makes the case wordlessly that diverting a few 0.1% of the budget away from reimbursing those in New Orleans living under levee walls who didn't want to divert the beer and videotape-rental money to pay for flood insurance, and instead spending it on researching rogue-missile MD, isn't necessarily a heartless and improvident decision.