Or maybe his son wants to prove himself..show the world that he is a big man
Yes, that is another theory. As is...
"The BBC's diplomatic correspondent Jonathan Marcus says: From the North Korean viewpoint this is about establishing a deterrence strategy over the South and defending its vital interests. An annual South Korean military exercise is under way across the country. The North Koreans demanded that this be halted. And when it went ahead, for whatever reason, this clash erupted."
Or...
"Choi Jin-wook, a North Korea expert at the Korea Institute for National Unification in Seoul, tells the New York Times that the incident is a "sign of North Korea's increasing frustration" at the US government's refusal to remove sanctions. "Washington has turned a deaf ear to Pyongyang and North Korea is saying, 'Look here. We're still alive. We can cause trouble. You can't ignore us,'" he says. North Korea's most urgent priority is food aid, he adds."