This seems like a heated debate

with most of you feeling that the US should just 'KICK THEIR TEETH OUT'

however, as some of u point out it is not AT ALL that simple.
The US will never attack North Korea, first of all because it has no strategic interest in it. The latest announced withdralwal of US forces ( which when completed will account for 98% of all army personnel) from South Korea confirms that. The US got involved in the Korean War only because it was folowing an ultimately bogus preventive foreign cold war policy aimed at stopping the so called 'domino effect' (which itelsf was proven worng).
The US stayed as long as it did only because it would feel embarassed to leave an 'ally' (South Korea) face alone the world's fifth largest army (yup that is correct

), however the North will never attack because it knows any gains will be heavily outweighted by the tremendous losses. All of their 'big talk' is well known to be a political trick aka 'strategic deception' but in this case the North cannot really deceive anyone, its strategy is mostly domestic-orientated (prove your opressed nation that the others are the bad guys

). North Korea is fully aware of all that and I assure you the US knows it even better. That is why it has pulled out and concentrated on more pressing issues.