The USA should have no response to any NK provocation unless and until American forces are injured (that's why they are there, as a tripwire to bring the USA into any renewed Korean war) or unless called in by the South Korean government to honor our treaty obligations. G-d grant this doesn't escalate to that level.
One small bright spot - this should shut up most of the lefties calling for us to bribe the Gargoyle into playing nice, at least for awhile.
I do wonder how long before the left demands that FBI agents be sent into North Korea to investigate and arrest those responsible for these murders.