The return of U.S. Army troops from their one year tour of duty in Iraq, and replacement with more army units, will put about 80 percent of army combat units either in Iraq, or just returned from Iraq. The returning units will be at a low level of readiness for at least six months because of troops leaving the service, taking vacations or transferring to other assignments. Most of those movements were put on hold while the units were in Iraq. With so few army units available for emergencies, one of the two brigades of the 2nd Infantry division in Korea may be assigned as a "deployable unit" (available for an emergency in some distant hot spot.) The 2nd Infantry division trains hard and keeps itself at a high level of readiness because of the constant threat of attacks by the North Korean army, or North Korean commandos (who have been raiding into the south, on and off, for four decades.) But now the 2nd Infantry division is going to be moved from the DMZ (the border with North Korea) to a position farther south. There, the American unit will act more as a reserve for the South Korean army. The South Korean armed forces have increased their combat capabilities considerably in the last decade, while the North Korean forces have grown weaker (while still posing a significant threat.) So it is felt that one of the American brigades can be used elsewhere in an emergency.