The United States is preparing to deploy anti-ship and air-defense missiles to Yonaguni, Japan’s westernmost island. Just 110 kilometers from Taiwan, the island is strategically important as China expands its military activity in the region.   The deployment is part of Keen Sword, a joint exercise scheduled for October 19 through 29. U.S. Marines will bring two systems to Yonaguni for the first time, according to Japanese defense planning documents cited by Stars and Stripes, a U.S. military newspaper.   One such system is called NMESIS, a mobile launcher carrying Naval Strike Missiles that can target ships roughly 185 kilometers away. The other is MADIS, a mobile air-defense system designed to counter drones, helicopters, and other low-flying threats.   The deployment is part of a broader U.S. Marine Corps strategy. Smaller, mobile units armed with missiles could make it harder for opposing warships to operate near Japan’s southwestern islands. For now, the systems...