Just outta curiosity...

... How come GOP Presidential hopefuls haven't promised to annihilate North Korea?

North Korea issues unusually specific threat

North Korea has a proven nuclear capability.
It does not play well with others.
It is the last bastion of a pure Communist state, with an autocratic leader completely out of touch with his subjects.

But Romney et al. are silent.

Could it be the simple fact that North Korea has no oil? (... not to suggest that Romney et al. are in the pocket of Big Oil...)

Just askin'.