South Korea launched today its biggest-ever civil defence drill amid high tensions over North Korea's deadly artillery attack last month and its nuclear programmes. The National Emergency Management Agency said the nationwide evacuation drill was the first of its kind since a civil defence law was passed in 1975. Sirens wailed across the country to signal the start of the 15-minute exercise. Most traffic quickly halted on Seoul's main street, Sejongno, and elsewhere in the bustling city centre.