A few links and then some thoughts. The Marmot has a couple of excellentposts and from the latter is this explanation of why S Korea residents are unhappy with the idea of the US attacking the missile base:
It’s probably also worth noting that there are probably a few South Korean officials who fear the Americans might actually respond to a test by delivering a world of hurt on the North via B-2 or F-117, and do I really have to explain why somebody within North Korean artillery range and a one-hour drive from a goodly percentage of the Korean People’s Army might not necessarily view that as a fortuitous turn of events?
Majikthise links (for the purposes of debate, as she clarifies) to an article by former Clinton officials Ashton B. Carter and William J. Perry where they argue that North Korea cannot be allowed to test its new long-range ballistic missile and propose precisely the course of action that the Marmot fears. My prefered option is that proposed over at Big Lizards namely that if America's Ballistic Missile Defense (BMD) programs are as capable as they are supposed to be then the prefered option would be to shoot the missile down. This would send a message not unlike that proposed in the initial article but without damaging any N Korean soil. It would also send a message to a number of other nations which couldn't hurt.
There are a couple of important details in my position which may differ (slightly) from the Big Lizard on. Firstly if possible the NK missile shoud be destroyed in its ascent phase, simply because that makes a far greater statement. Secondly I personally think an attempt should be made even if we are unsure of the success or not because the chances of getting another live test are slim and from a practical engineering sort of view I would really prefer to have a BMD system proven tested before it goes into full production. In fact even if this take down fails, so long as a decent effort is made a lot of valid information will be yielded and the message to potential US attackers will that a single missile is no guarantee of anything other than a retaliatory strike. Indeed, were I in charge of the Pentagon's PR, if the take down fails I'd be sending a public letter to Comrade Kim thanking him for the opportunity for a live test and telling him that many lessons were learned - indeed I might even give him some money (a suitcase of counterfeit $100 bills perhaps) as a thank you present.