If they shoot at one bomber , the other bomber releases the bomb which destroys N. Korea.

I googled Pershing missile but it is not air launched. We probably have some on the ground in south Korea. Over 1000 mile range and about 80 kilotons nuclear. Hopefully we've taken these types of missiles out of Europe and Ukraine. No warning so no defence is possible. It's called mutually assured destruction.

But I'm sure the bombers may have carried the air launched missiles close to or over n Korean air space. They may have a greater range and payload than a Pershing because they're fired from a high altitude and speed. 

We continually practice non-nuclear invasions with thousands of n Korean troops. It's called regime change. The n Koreans know we mean business. That's why they are developing a nuclear weapon - for their own self-protection.