General Vincent Brooks has a tough job. As the commander of all American forces in Korea, he is responsible for the lives of some 20,000 U.S. troops. That’s big. But if North Korea attacks South Korea, the four-star general suddenly becomes the leader of up to 4 million joint U.S.-South Korean regulars and reservists.
Since 1981, the general staff on the Korean Peninsula has been organized as a combined staff, led by an American four-star general with a South Korean deputy commander of equal rank. If attacked by North Korea, this Combined Forces Command will command the joint air, sea, and ground defenses of the South.
The national duality of shared command exists throughout the CFC command structure. Anywhere an American officer is in command, the deputy is from the Republic of Korea. Anywhere an ROK officer is in command, the deputy is an American.
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This structure exists from the tactical level all the way up to the overall commander.
This is not true for other nations who share a mutual defense treaty with the United States. In Japan, for example, the U.S. will still come aid in defending the nation, but the Japanese would retain their overall command structure.
When the Republic of Korea and American military do their annual, 200,000-man strong joint exercises (you know, the ones that piss off the North Koreans as they quake in their boots), the Combined Forces Command oversees that exercise.
For General Vincent Brooks, those exercises must be a necessary deterrent from North Korean aggression, even as the war of words exchanged between the Kim Regime and the Trump White House escalate.