American plans to send one of its two infantry brigades in South Korea to Iraq caused some nervousness in South Korea. But the number of American combat troops has been steadily falling since the end of the Korean War 51 years ago. During the 1960s, there were six American  infantry brigades in South Korea. Now there are two, and after this Summer, there will only be one. There will still be over 30,000 American troops in South Korea, most of them Army support troops, air force personnel and some navy and marine personnel.