Opponents of a possible North Korean long-range missile test stepped up a diplomatic drive to stop the launch Monday, issuing a barrage of warnings to the reclusive nation and threatening retaliation if it goes ahead. North Korea has taken apparent moves toward test-firing a missile believed capable of reaching the US, putting the region on alert. Pyongyang was silent on the launch, but vowed to bolster its military deterrent, in comments carried through its state news agency. The chances of a launch were unclear, in part because of the weather at the missile site Monday. There were cloudy skies and chances of showers in the area, with fog along the coast, said Kim Duck-wan, an official at the South's Korea Meteorological Administration. Japan, the United States, Australia and News Zealand all cautioned the impoverished country that a test of a Taepodong-2 missile would bring serious consequences and further isolate the regime.