“Recently, the military has taken a back seat to the State Department, where U.S. officials continue to push diplomatic and economic measures, hopeful, with the help of China, it can pressure the regime to halt its provocations voluntarily. But if diplomatic efforts fail and a conventional war ensued with all but nuclear weapons being deployed, experts agree that the scenario would involve massive amounts of U.S. and South Korean forces in the first days — and possibly drag on for many months or longer.”
Source: War with North Korea: An inside look at how U.S. troops would respond worldwide