Answers (2)
What North Korea says is that its angry at sanctions placed upon it because of its nuclear tests and also angry at its treatment by America in the 1950s.
What is actually happening is that North Korea's regime has used massive propaganda to keep its people oblivious to the outside world for decades. With the advent of mobile phones and the internet, people in North Korea are slowly starting to become aware that what's happening there is not normal. When a government starts losing face or popularity, one way of rallying the figures is by sabre-rattling or even going to war. It worked for Margaret Thatcher, George W. Bush, Napoleon and Adolf Hitler.
