PANAMA CITY -- Preparing for the possibility of economic sanctions against North Korea, U.S. Defense Secretary William Perry drew up contingency plans that included sending dozens of aircraft and ships and hundreds more troops to the region. Perry, who divulged a rough outline of his proposals Thursday on a flight to Panama to visit U.S. troops, laid them out at the White House a week ago as tensions were rising over North Korea's nuclear program. Tension eased Wednesday when President Bill Clinton announced that the North Koreans had confirmed they would not refuel a key nuclear reactor or reprocess spent fuel into plutonium, while high-level talks between Washington and Pyongyang proceeded.