The United States and South Korean troops will stage a 10-day computerised war games called “Ulchi Freedom Guardian” tomorrow as part of a flurry of military drills in response to North Korea's alleged torpedoing of a South Korean warship that left 46 sailors dead in March. General Walter Sharp, who heads some 28,500 US troops based in the South, described the exercise as one of the largest joint staff directed theatre exercises in the world. In July, South Korea and the United States held a massive joint naval and air drill in the Sea of Japan. Last week, the South staged its largest-ever anti-submarine drill near the disputed Yellow Sea border.