No panic with North Korea & US leaders crazy talk. Once the US can develop its defensive & offensive laser weapons to reliably defeat missiles at any stage of its trajectory, that would be the time nuclear tipped missiles from N Korea, Iran, China or Russia will no longer be such an extreme threat to the US.  However that does not stop the threat of a Muslim extremist from smuggling in a compact nuclear weapon into the US & detonating it a packed NFL or SEC college game.  Better to tone down Trump's empty threats, & they are empty, as the US would never preemptively strike N Korea.  Also clear Trump not too worried about N Korea taking out Seoul in S Korea because that is N Korea's current reliable range of missile attacks as it will take many more years, missiles tests & obtaining missile/ nuclear weapon technology from Russia, China or Iran before N Korea is a direct military threat to the US as is Russia & China.  Advanced US laser weapons technology will tip the balance to the US