My theory on why North Korea has stepped up its provocation of South Korea since their nuclear missle tests is that they see this as a tug-of-war.
Suppose that North Korea wants to keep its nuclear weapons program. If they hadn't sunk a ship and bombed a city, world leaders would currently be pressuring North Korea to stop making nuclear weapons. Instead, they're pressuring North Korea to stop doing something (make provocative attacks) that North Korea doesn't really want to do anyway. And when North Korea (temporarily) stops attacking South Korea, everybody can go home and say they "did something about North Korea". And North Korea can keep on making nukes.
I've seen the suggestion that some or all of North Korea's unpredictable provocations have as much to do with their internal politics as with any coherent foreign policy strategy.
It is a classic ploy for uncertain and troubled regimes to have an outside enemy to blame for problems.
My theory on why North Korea has stepped up its provocation of South Korea since their nuclear missle tests is that they see this as a tug-of-war.
Suppose that North Korea wants to keep its nuclear weapons program. If they hadn't sunk a ship and bombed a city, world leaders would currently be pressuring North Korea to stop making nuclear weapons. Instead, they're pressuring North Korea to stop doing something (make provocative attacks) that North Korea doesn't really want to do anyway. And when North Korea (temporarily) stops attacking South Korea, everybody can go home and say they "did something about North Korea". And North Korea can keep on making nukes.