There's always the possibility of a peaceful resolution. Kim might one day decide he's better off making friends rather than enemies, or a more moderate leader might stage a coup or something. People thought the USSR would be around forever, and then suddenly in went to pieces without anyone having to blow it up. But what are the odds of that actually happening? Nobody really knows. If they're remote, then getting it over with now is probably the best approach. If they're decent, then waiting might be better. It's a difficult decision to make.