The Commander-in-Chief of the US Armed forces definitely has the power and ability to 'fire' Kim Jong Un in the exact same way that President Obama 'fired' Osama bin Laden!

He doesn't have to use a SEAL team, but he has the ability, as Obama would say, "with the stroke of my pen or a telephone call" to accomplish the task!

And that would probably be the best solution to the North Korean problem.  Korea is a war under 'cease fire'.  The head of a nation with which we are at war is a fair target.  

The US government has assassinated other leaders just for political and economic advantage.  Why shouldn't Trump kill a man threatening to nuke US citizens?