SEOUL: Sirens wailed on Wednesday as South Korea held its first nationwide air defence drills in six years to counter North Korea's growing nuclear and missile threats, but many people appeared to ignore calls to seek shelter.The drills are a key element of the annual Ulchi civil defence exercises, held alongside the Ulchi Freedom Shield drills, which South Korean and U.S. troops began on Monday, to improve responses to a North Korean attack or other contingencies.Air-raid sirens blared at 2 p.m. (0500 GMT) on a rainy but hot...