Interesting. I had never heard about the N Korean pilots in Vietnam. However, it still doesn't explain why the US didn't retaliate against the act of war committed by N Korea against the Pueblo.
Ask LBJ and McNamara. While you are at it, ask Jimmy Carter why he didn't retaliate when the Iranians took DIPLOMATS and embassy employees as hostages. That was also an act of war and the Iranians are still at war with the US. The end to that one might be in sight, however.