In addition to the aerial and naval bombardment, United States Marine Corps officers briefed their units on the supposed Gunsan landing within earshot of many Koreans, assuming that the information would make its way to KPA leaders through rumors or spies. On the night of 12–13 September, the British Royal Navy landed U.S. Army special operations troops and Royal Marines commandos at Gunsan, making sure that enemy forces noticed their supposed reconnaissance of the area. U.N. forces also conducted rehearsals on the coast of South Korea at several sites with conditions were similar to Inchon. These drills enabled U.N. forces to perfect the timing and actions of the planned Inchon landing while simultaneously confusing the North Koreans as to the actual landing site.