South Korea have already began bombing the borders
http://metro.co.uk/2017/08/29/south-...force-6886434/
the bombs were dropped in tests on the South Korean side of the border, but in show of the force they can display to North Korea is they decide to attack.
All the bombs landed in perfect positions & can wipe out 11mtrs of concrete, wiping out NK cities would be possible & simple to do for South Korea