I feel that there are tonnes of other options left. Diplomacy with the Chinese, sanctions, covert operations. At the moment Trump is bloviating and Pence is standing in the DMZ looking grumpy. Strikes me as the total opposite of the way we should be handling a country with very little to lose.
All that aside, surely this is something that Japan and South Korea should take the lead in. Perhaps the UN.
That's the end game. It's ultimately a bluff to force action where there's previously been inaction.
Not a Trump fan, but can't fault this personally - it's what I'd have done.

