SEOUL, South Korea (AP)   Japanese, South Korean and U.S. missile-destroying ships set sail to monitor North Korea‘s imminent rocket launch, as Pyongyang stoked tensions Monday by detaining a South Korean worker for allegedly denouncing the North‘s political system. North Korea says it will send a communications satellite into orbit between April 4 and 8. The U.S., South Korea and Japan suspect the regime is using the launch to test long-range missile technology, and warn it would face U.N. sanctions under a Security Council resolution banning the country from any ballistic activity.