We continue to reposition our forces on the Korean peninsula to move them away from the DMZ. There, our troops served less as a tripwire to deter North Korea as North Korea's power waned in relation to South Korea's power, and more as convenient hostages who could be threatened with artillery barrages (which could include poison gas).
The map of our planned deployment areas when completed in six years or so:
Our forces will be concentrated south of Seoul where they can serve as a mobile reserve and support ROK forces defending Seoul, and in the southeast where our reinforcements can pour in.
This gives us far more freedom of action if we need to attack North Korea's nuclear facilities. With no Americans easily in range to kill in retaliation, Pyongyang will be very unhappy with this change.