Tens of Thousands of South Korean and U.S. Troops began a military exercise simulating an all-out north Korean attack, as Pyongyang threatened a pre-emptive strike on forces participating in the drill. The two-week annual Ulchi freedom exercise is largely computer-simulated, but still involves 50,000 Korean and 30,000 U.S. Soldiers. The drill always triggers a spike in tensions on the divided Korean Peninsula, and this year it coincides with particularly volatile cross-border relations following a series of high-profile defections. The Seoul Urged all Citizens to be on guard against “North Korean Terror Threats” and warned of possible assassination attempts on defectors and Anti-Pyongyang activists in the South