Despite all the talking heads' anxiety about a war with North Korea, the real strategy is to cause regime change from within (probably a military coup). Kim Jong Un will try to hold onto power by any means, but his generals are not going to commit suicide on his behalf by inviting a full military response by the U.S.
Instead, the U.S. (and China) are ratcheting up pressure on the NK leader to take some action which will provide his generals with a coalescing excuse to remove him from power. After this occurs, these generals will agree to the reunification of a nonmilitarized Korea (on the condition that they receive full pardons). This will allow the U.S. to remove its troops from Korea and end any threat to China from Japan having to create its own nuclear deterrent.
Instead, the U.S. (and China) are ratcheting up pressure on the NK leader to take some action which will provide his generals with a coalescing excuse to remove him from power. After this occurs, these generals will agree to the reunification of a nonmilitarized Korea (on the condition that they receive full pardons). This will allow the U.S. to remove its troops from Korea and end any threat to China from Japan having to create its own nuclear deterrent.